This is the screw that both retains the upper portion of the SPYDER EXTRA foregrip whilst serving as a transfer port. The threading here is .825x14, which corresponds with a paintball tank valve, meaning, you could thread your paintball tank directly into this threading and use it in the foregrip's position instead (see illustrated in the gallery lineup). It acts both to retain the upper part of the foregrip to the receiver, w/ enough strength to be able to handle the extra strain from a gas tank threaded on directly and as a transfer port

This screw of course, is made from solid steel, not aluminium, so it will be able to handle the abuse you might chuck at the foregrip. 

If you might not be of a mind to fit this screw yourself or have tried to do so, but find that the gas is leaking around this part (possibly due to a missing / damaged or worn O-ring - then please don't hesitate to reach out to us - we are fully equiped to asssit you - you'll just need to get your marker here by us in person or by courier, alternatively, we can arrange for the courier from our end.

 Technical Specifications;

If you might be unsure as to how to strip / disassemble the SPYDER XTRA, partricularly to get to the area to replace the machine screw on this marker, likewise, how to fit it correctly along w/ the other associated seals to create a gas-tight fitting, then please see;