This clamp is 11" wide and the center can be expanded up to 5".  It is made of sturdy plastic with 4 - 4 5/8" rubber suction cups, a tightening rod and an adjustment wedge to level the seam for less sanding.  This is the best clamp to use for larger seams (kitchens, bars, vanities, etc.).  A minimum of (2) SR4X clamps is suggested to be used on a average 25" size seam.