Jefftron Leviathan V3 Optical Computerized AEG Trigger Board (Bluetooth)Trigger not included. The Leviathan V3 optical is one of the most advanced ETU (electronic trigger unit) on the market It has all optical sensors for better handling and durability Build in wireless communication for quick setup using iOS or Android smartphones! Foam on the trigger makes great hair trigger mode Unique Real feel trigger system (RFTS), spring simulates trigger resistance like in the real AK74. It adds secondary resistance with release