The Echo Sport is an economical pull and release trigger for the AR-15 Platform. The Echo Sport has the functionality of the Echo AR-II, the only difference is that you select the echo mode from a paddle rather than the safety sector. The Echo Sport is designed to function in the AR-15 Platform. The Echo Sport gives you all the functionality of the original AR-II at a more affordable price. It is more efficient, less complex, and most importantly, less money.