The VEX short for conVEX is the architectural culmination of ergonomic design and functional efficiency. The objective was to conserve the pliable comfort of the stock polymer shoe while preserving the rigid actuation of a metal trigger. This design is the first of its kind. Convex profile for the ultimate in comfort and ease of purchase  Reduced trigger width creating a more suitable finger pad to surface area ratio Longer blade style trigger safety increasing stability to the shoe body and enabling quicker disengagement Bilateral trigger safety stops for consistency and safety Stainless steel set screws for ease of installation and cleaning 6061 billet aluminum for durability (tensile strength of 45,000 psi) Laser etched trigger face for increased traction Minimized pre travel for more efficient purchase Reduced over travel for faster follow-up shots 100% American made  This shoe is sold with a spring kit to minimize drag and reduce break weight while maintaining 100% primer strike reliability. SPRING KIT INCLUDES: 4.5lb striker spring, reduced power safety plunger spring from ISMI.*V1 is shoe only  current lead time 24hr 43,43X&48 must only be used specifically for those models. Do not interchange all model only into 43, 43X &48