Single set back

Single set back (also known as the "Lone Setback" or "Singleback" or "Ace" formation or "Oneback" or "Solo") is an offensive base formation in American football which requires only one running back (usually a halfback) lined up about five yards behind the quarterback.^[1][2] There are many variations on single back formations including two tight ends and two wide receivers, one tight end/three wide receivers, etc. The running back can line up directly behind the quarterback or offset either the weak side (away from the tight end) or the strong side (towards the tight end).