This is Pulse’s 18mm female to female adapter. High quality accessories from Pulse! This is useful to change a joint on your rig so you can use your existing slide or nail. These are also a wise investment to have an adapter take any potential heat damage, so if there is ever an overheating event, damage is to the adapter and not your potentially expensive rig! 18mm female to 18mm female adapters are often useful, and this is a quality accessory from Pulse.