Review: Milwaukee’s M12 Insider Ratchet Gets In There And Gets it Done

The designers behind Milwaukee’s M12 Insider ratchet understand the limitations of most cordless models. They set out to change things with this design and loaded it with features such as a compact head and special low-profile sockets that actually allow you to use a cordless ratchet where space would otherwise prevent it. That, paired with some generally impressive performance specs, makes for a seemingly excellent addition to the M12 line. 

As we all know, what looks good on paper doesn’t always reflect reality. At least, that’s what kept going through my mind when Milwaukee sent me an Insider cordless ratchet for review. It was perfect timing, too, as I’m diving into some really claustrophobic situations that would really put the innovative features of the Insider to the test. 

Right away, I’ll say that I really like what Milwaukee put together here. The Insider made me a believer in cordless ratchets. It’s no small investment, though. This thing commands a pretty penny and that means anyone who’s interested in it should do a lot of research up front to determine if it’s the right fit for their collection. That’s why I’m happy to talk through all of the things the M12 Insider got right to earn my respect. 

Milwaukee’s M12 Insider ratchet is all about getting you into tight spaces that cordless ratchets generally are useless for. What makes this cordless ratchet so special is the head itself. The lack of an anvil is the first indication of how different this thing is from conventional models. Instead of an external drive that attaches to normal sockets, you have a hex-shaped opening that’s designed to work with Milwaukee’s special Insider sockets. 

The Insider sockets feature an hex shank that fits into the head of the ratchet, creating an incredibly low profile piece. As a matter of fact, Milwaukee claims it has the world’s smallest cordless ratchet head, which is easy to believe when we look at the measurements. 

Without any sockets attached, the M12 Insider’s head, including the selector switch, measures just over an inch in depth and has a width of about 1-1/8 inches. With a 9/16-inch Insider socket attached, the depth increases to just over 1-5/8 inches. For comparison, Milwaukee’s M12 high-speed ratchet has a head width of 1-5/8 inches, with a depth of around 2-1/8 inches with a 9/16-inch socket attached. 

I also compared it to a couple of Craftsman’s 180T Overdrive ratchets—full review coming soon. The 3/8-inch drive ratchet has a head width of 1-3/8 inches, with a depth of 1-3/4 inches with a 9/16-inch socket attached. The 1/4-inch drive version has a width of just over an inch and a depth of 1-7/16 inches with a 9/16-inch socket. These ratchets are designed to give an advantage in tight spaces, so a cordless ratchet with a head size that lands between the two is pretty impressive. 

A compact head isn’t all the Insider does to separate itself from the pack. The unique design allowed Milwaukee to change the game with pass-through sockets for a cordless wrench. The included metric socket set spans from 8mm to 21mm with sizes 8mm to 15mm being pass-through sockets. Available SAE sockets range from 5/16-inch to 3/4-inch, with 5/16-inch to 9/16-inch sockets being pass-throughs. I should also mention that the metric socket set that it comes with includes 3/8-inch and 1/4-inch drive anvils so you can use it with regular sockets and a 1/4-inch bit adapter to further bolster its versatility. 

On top of that, the Insider ratchet also has an extended reach with an overall length of 15-1/4 inches. So, what we’re looking at here is a low-profile extended-reach cordless ratchet with pass-through sockets. That’s an awesome package already. It’s also got some impressive performance specs to boot. An operating speed of 350-rpm and a maximum torque rating of 60 ft-lbs makes it a respectable cordless ratchet by any standard. 

It’s really hard to argue with the potential of the Insider, but I’m sure most of you will agree that stats are only relative in a laboratory. Getting greasy is in order to truly gauge what it brings to the table. 

The Insider showed up right as I’m converting my 1969 Dodge Charger to a Heidts 4-link at the rear and a Pro-G IFS at the front. As soon as I got the Insider out of the box, I started beating the crap out of it and haven’t let off since. I can say, without a shadow of a doubt, that the stats translate to real-world results.

The Insider’s low-profile head, impressive performance, and pass-through sockets really do make this cordless ratchet stupid-good. It’s made light work of tedious jobs that I hate doing, totally transforming the mindset I approach projects with from hereon. That’s huge. 

The first job I used it to do was to drop the fuel tank out of my car so I could get to work on the 4-link conversion. The bolts that the tank hangs on are exceptionally long, and there’s not a whole lot of space for work. It’s a total pain in the neck. Usually, it takes a stubby combination wrench and a ton of patience to work through. The Insider ratchet got it done in a hurry with the pass-through 9/16-inch socket.

Another situation where the Insider really flexed its worth is when removing the starter from the engine. Thanks to the headers, it’s a pretty annoying task. Usually, it’s a whole song and dance with yet another stubby wrench on the bottom bolt that takes way longer than it should to remove. It’s easy to lose your mind as you’re swapping the wrench around from side to side while your hand cramps up and claustrophobia sets in. The Insider got right in there and saved me from my personal Hell. 

While these situations definitely played to the strengths of the Insider, they’re far from the only work it’s seen in my shop. The project I’m involved with has been a massive lift that has me stripping every mechanical part out of the car. I’ve found myself grabbing the Insider almost every step of the way. I’ve beaten on it, dropped it, and have given it a real workout in every way you could think to, outside of deliberately trying to break it. It has proven to be an awesome tool all around. It’s even easy on batteries, which is not the case with the M12 die grinder and bandfile I’ve also been beating the daylights out of. 

The only real problem I could find with the Insider is how expensive it is. This ratchet has a starting price of $299.00. That doesn’t seem all that bad, especially considering that cost includes the metric socket set. However, that doesn’t include the batteries. That version of the kit sells for $399.00. And if you want the SAE Insider sockets, you need to dish out another $49.00. All in, we’re looking at a $450 cordless ratchet.

One common complaint I’ve heard about the Insider is that it tends to skip teeth when you break fasteners free manually. I haven’t run into that problem. Though, if a fastener is really stubborn, I’m not using this to break it loose—even if this thing is built to take a licking. Instead, I grab a breaker bar and let it do the bull work while this just cycles it free. I’m confident in saying the Insider will hold up just fine as long as you go about things the same way. 

Milwaukee’s M12 Insider ratchet is an all around killer tool and it’s really hard to beat when you look at everything it brings to the table. I know a lot of folks will disagree and argue that a faster or more powerful model is better, and I won’t challenge them. Sometimes, those features really are more important than slipping into tight spaces. But, for me, the Insider is the way to go. It’s incredibly versatile, it’s built really well, and you’re going to get a ton of use out of it regardless of whether you’re a DIYer or a professional. 

Many people are going to pass up on the Insider because of the cost. It is money well-spent if you’re a serious wrencher, though. It does a lot to improve workflow and you are investing in the M12 line, which has a ton of excellent tools for automotive work. However, as a person who’s made it this far without using any cordless ratchets on their personal projects, I understand not tripping over yourself to get your hands on one. Let’s face it, it’s a great tool, but it is something you can live without. 

That said, I’m just a DIYer, and I primarily work on a classic muscle car. Take my opinion with a grain of salt. I encourage anyone with different opinions, especially those who work in the trades, to share their thoughts in the comments section. My goal here is always to help readers walk away with a holistic understanding of what’s best for them, even if it’s contrary to my take on the subject. Your comments are a key component of that.