Black Steel Grip Control folding thumb rest / gas pedal for a Sig P226, size 3, suitable for those with L/XL hands.  This replaces the factory takedown lever and provides an index point for your support hand thumb, acts as a gas pedal while shooting but folds up flat for holstering.  Works great, just swapped it out for a different size. Quick and easy install.  

Asking $50, shipping included if needed.