The VICTRA-20 internal choke is a specialized choke that sits inside the front of the suppressor. The choke of a shotgun determines shot shape and as such it is an important part of any shotgun. The Victra-20 places the choke at the end of the suppressor in the optimal place. Our three different choke sizes are all made of 17-4 Stainless Steel and are machined specifically for our VICTRA-20 20ga modular shotgun suppressor. Material: 17-4 SS Finish: None Gauge: 20 Made in the USA.