Solid albeit pricy alternative to an a3 stock & sbr - SB Tactical HKPDW HK Brace for HK MP5/HK53/MP5K

First, a handy tip. Before installing, unscrew the 2 screws at the bottom, then slide it on and insert the screws later, it'll save you major headaches, at least on the MAC5.
Using the brace as designed, it works well. Unlike some competing braces, there's plenty of extra play on the arm strap and the rubber is flexible enough that you can easily fit your arm in there, yet it's easy to keep it in place once you tie down the strap. I'd recommend when shooting this way you do not extend the brace so its easier to use the sights on the weapon.
Should you choose to place the brace against other parts of your body, it also excels. The rubber material absorbs alot of the recoil which is already minimal with the MP5, and the cheek weld, while inferior to a folding stock (and presumably the SBT-5) is manageable if you place it high enough.
Regardless of which way you use it, it is much easier to hit your target compared to freehanding it. I was missing at least half shots just trying to freehand it before I got the brace, and while I didn't keep track when using the brace, it was much easier to stay on target.
The brace itself is very well built and sturdy. It does not wiggle and does not feel cheaply made. Once installed it's easy to slide the Brace forward and backward, or lock it in the desired position. You can also quickly and easily slide the brace off entirely and return to a mostly stock configuration, but it's also designed well enough that this will not happen unless you want it to. As an added bonus, the many discounts provided by opticsplanet allow you to get it at least 10% off the listed price with free shipping

My main issue is just the price. The extra $100+ compared to an SBT-5 is a hard pill to swallow. At this price point you're starting to get into the territory of a $200 tax stamp and cheap aluminum airsoft stock (though to be fair it's still a fraction of the price for even 3rd party MKE A3 stocks let alone official H&K stuff). I chose this because it was hopefully built better, and to be fair it does seem to be, I'm not afraid to be rough with the brace, which would not be the case with the cheap aluminum VFC airsoft stocks.
A big reason why people love telscoping stocks on the MP5 is because they just look stylish and cool. The bulky rubber and strap do look kinda stupid, albeit still better than a folding stock or brace IMO. If you only care about function, then no big deal, but if you want something that looks cool, or has a smaller footprint, consider the SBR route.