This is a Wilson Combat Safety known as the Bullet Proof, model 6BNBP.
The ultimate thumb safety for your carry gun" the Wilson Combat Tactical Bullet Proof thumb safety is perfectly shaped for everyday use and precision machined from a solid block of hardened billet steel. The safety shaft is cut to maximum dimensions for a snug fit in even the most oversize 1911.
Features:
CNC Machined Billet Steel
Snug Fit
Minimal Fitting Required