Apeks Book Screw Kit 2-PackThe WTX and WTX D Series is a selection of harnesses, buoyancy cells and accessories which offer unparalleled versatility due to the modular nature of the whole system. Each component can be configured into a highly technical rig for those trained to push the limits, or scaled down to make a travel friendly set up suitable for any diver. Book screws can be used to attach a wing to a back plate or to anchor an accessory to a back plate. Two sizes are