This is a Seekins Precision Gas Block, model 0011510031.
The Seekins Precision Low Profile Adjustable Gas Block lets you to fine tune your rifle's gas system for smoother cycling and operation. Operation is easy" simply turn the gas regulating screw in to lessen the amount of gas and out to add more gas" then use the brass tipped set screw to lock the setting in place.
Features:
Melonite Coated
Field Adjustable
.750";Reduced Wear and Corrosion
