The Performance II is a two ply head manufactured with Aquarian's Vacuum Tuned Process which eliminates air bubbles and wrinkles between the two plies. The two 7mil plies are only sealed at the edges which tame unwanted overtones and puts a focus the low frequencies. The PFII is designed for loose tuning to deliver that low, fat, punchy tom-tom sound that were a big part of classic rock and roll records. Frequency control that adds focused power is built right into this head. The PFII is a great head to use to upgrade the sound of low priced kits.