I emailed them asking about NJ legality and this was their response:
Thanks for the inquiry. We need to update our website to reflect NJ use. NJ is our second best selling state, right behind CA. Being in CA, We're not as well versed in NJ firearm laws as we are with CA laws, however, we sell a ton of Stock-Loks to NJ. If NJ laws simply state that no telescoping stock, Stock-Lok eliminates any telescoping option, since it removes the adjustment mechanisms and fixes the stock to one place. It also requires an external tool and complete disassembly to adjust the stock. If NJ law requires the stock to be permanently fixed to one position, Stock-Lok can be used below to accomplish this.
Some of our customers in NY and a few in NJ have opted to use epoxy to make the use of Stock-Lok "permanent." There are two options with this method: 1. Epoxy the Stock-Lok into the slot position you prefer, or 2. Epoxy the open top portion of the socket head screw after it's installed so the tool can not fit in it. Both of those options make the installation "permanent." We've definitely had NY customers do these options, and I think a few NJ customers have opted to do one or the other of these options.
If you have any other questions, just let us know.
Range Roll Team