This sponge features an extra fenestration which allows it to lay flat when wrapped around a drainage tube. without it, the sponge will pucker, decreasing effectiveness by allowing fluids to pool around the drain tube. it#s a simple feature that most other drain sponges do not offer. includes all the benefits of non-woven avant gauze. each 6-ply rayon/polyester sponge is highly absorbent, low-linting and fast wicking to wound. size: 4" x 4", quantity: 600 total sponges.