The black DLC (Diamond-Like-Carbon) physical vapor deposition finish on essential action parts comprises chromium and tungsten underlayers that give superior corrosion protection. So your ETU will continue to work as smooth as glass even under heavily fouled conditions for years to come.- all while reducing wear due to hot powder gases. 

Features:

• Drop In
• Two stage
• No adjustment screws
• CNC precision machined
• H13 steel and treated with DLC finish
• Positive trigger reset
• 4 - 4.5 lb trigger pull

Compatibility Notes:

• Colt brand rifles made for commercial use between 1991 and 2009 will generally have a proprietary trigger pin size of .169” and are not compatible with any Wilson ETU
• Colt rifles produced with pinned-in sear blocks are not compatible with any Wilson ETU
• Wilson Combat ETU is not compatible with the Bushmaster ACR
• The MR556 and any other AR style rifle with a firing pin safety mechanism in the bolt carrier is only compatible with the ETU Two Stage Models (TR-ETU-M2)
• With .22 LR AR conversions or complete .22LR caliber AR-pattern rifles it is recommended that the standard single stage ETU (TR-ETU) or two stage ETU (TR-ETU-M2) trigger be used along with high or hyper-velocity ammunition for best reliability
• The ETU is compatible with the S&W MP-10 .308 AR but the rifle's ambidextrous bolt catch must first be removed to install the trigger unit
• Because of the short fast reset of the ETU always use a firm grip and solid hold when shooting from the bench or prone to ensure that bump firing does not occur.

NOTE: Wilson Combat AR-15 Enhanced Trigger units will reliably function in any standard USGI style AR style lower receiver with standard GI trigger pins of .154” diameter regardless of caliber including 7.62/.308 length AR receivers.