Choose surplus or new (new is currently out of stock).
New US semi auto sears are CNC made and professionally heat treated.
Best sears on the market.
For Pistol or Mini sears see link below.
Parts must be inspected and tested by a qualified and competent gunsmith or armorers before use in a firearm.
Not all firearm parts are interchangeable; use of surplus parts without proper knowledge could cause a firearm to malfunction and cause property damage, injury or death