Fostech ECHO Sport Binary Trigger For ARsThe Fostech ECHO Sport Binary Trigger is an economical yet high performing upgrade for AR platforms. This binary trigger allows one round to fire on the pull and another on the release of the trigger, increasing your firing speed while maintaining control. The selector paddle inside the trigger well makes switching between Semi Automatic and Echo modes quick and intuitive. Compatible with Mil Spec AR lowers, this durable drop in trigger offers