We have gotten an APS ASR107 M4 URX Raptor AEG recently. But it expects you to use a LiPo battery in its stock. But we preferred to use a 9.6v NiMh battery. It barely fits in the shoulder stock when the stock if fully extended. In CQB scenario, the fully extended stock is just too long. Luckily, the shoulder stock has a rail on it, which is perfect for a battery box.
Read about this shoulder stock and battery problem in this article: APS ASR107 M4 URX Raptor Review.
The Cyma C.69 MP5 Batteries Case seems to be the perfect size for our application. It comes in a nice cardboard box (see photo below).
It's curious why the packaging markets it for the MP5. The MP5 doesn't have any rails for the battery box. And the battery box can be used on any gun (with Picatinny weaver rails).
We used this battery box in a real-world airsoft application here: Extending the Shoulder Stock Rail.
The battery box is slimmer and shorter than the PEQ-2 battery box. Therefore, it's good for some applications, like the should stock. It has a number of dummy features on it (see photo below). Sadly, the front dummy lens elements does not have a plastic transparent lens cover. If you want to mount a laser or light into it, you'll have to drill the holes yourself. But with a battery box this small, I'm not sure if it would have sufficient space.
There is a Picatinny weaver mount bracket on the bottom of the battery box (see photo below).
The mounting bracket can be removed from the battery box. But it doesn't serve any purpose to remove it, because it can only be attached to the battery box in one position (see photo below). it would have been nice if the mounting bracket can move back and forth.
Unlike the PEQ-2 battery box, the C.69 battery box has a snap-on cover that you can pull off to reveal the box. In contrast, the PEQ-2 battery box has a screw to fasten the cover. Both has advantages and disadvantages.
The snap on cover has a hole for the battery wire, rather than a slot. So your battery connector has to be small enough to fit through the hole. Luckily the mini-Tamiya connector fits through that hole.
Small type batteries fits into the battery box with room to spare. The photo below shows a 8.4v NiMh battery inside the battery box.
The full-size battery, used in RC cars fits as well. But only the 7.2v full-size battery will fit. It does stick out just slightly (see photo below). So with this box, you can use full-size 7.2v batteries with your airsoft gun.
Overall, this battery box is excellent for some application. But if you are looking for one that not only serve as a battery box, but also as a laser sight and light container, you may need something bigger.