Works well to connect otto nb tac's to a helmet - OTTO Engineering NoizeBarrier TAC Helmet Mounts

These are sturdy and have both metal and plastic parts. The plastic seems high quality and hasnt deformed at all. They are pretty easy to pry of the headset if you are going to switch between helmet mounts and over the top.

As far as mounting to helmets, they sell the 2 models listed but no MLOK. With that being said it is possible to mount to MLOK and it is very sturdy if you buy the HHV RAK kit and 2 M4 screws.

There is the little compartment on each side that allows you to store an extra battery, which you'll rarely need.

Overall, good quality and I like this better than how peltors mount.