DynaDerm Hydrocolloid Dressings are easy to use and require dressing changes only every 3-5 days and do not cause trauma when removing. Hydrocolloid dressings are a gel type of dressing that absorbs liquid from wounds and have a soft, cohesive feel. Sterile, hydrocolloid dressings are water-proof and stay on even when wet. Dressings measure 2 x 2, 20 sterile dressings per box.