POWERSONIC CLEAR BASS DRUMHEADS FEATURE FOCUSED LOWS WITH INCREASED ATTACK. CONSTRUCTED WITH 2-PLIES OF 7-MIL AND 5-MIL CLEAR FILM, POWERSONIC CLEAR BASS DRUMHEADS PROVIDE TWO SPECIFICALLY PLACED SUBSONIC DAMPENING RINGS AND EXTERNAL SNAP ON DAMPENING SYSTEM WITH IMPACT PATCH FOR MORE ATTACK. THE EXTERNAL SNAP ON DAMPENING SYSTEM ALLOWS YOU TO CUSTOMIZE YOU SOUND FOR DIFFERENT PLAYING SITUATIONS. AVAILABLE IS SIZES 18 - 24.