This trigger has an aluminum alloy housing with machined and hardened steel work surfaces which are all held to tolerances less than .0005". This ensures durability and repeatable performance. Trigger comes pre-set from the factory at 3lbs and is adjustable from 1-1/2 to 4 lbs. The trigger offers a serrated 3/8" wide trigger for better control and is adjustable for creep, overtravel and backlash. The 510 trigger is unique by design in that the safety blocks the actual trigger instead of the sear, as a result the bolt can be operated with safety "ON". For use in right hand actions only.