The Muc-Off Expanding Microcell Expanding Sponge is Muc-Offs premium quality sponge. A lot more thought has gone behind this simple cleaning utensil than you think. The sponge is contoured to an ergonomic shape so its more comfortable when in use and to also maximise surface area for cleaning. The sponge is vacuum packed in the packaging to take up less space where ever you put it. Don't be fooled, when you have opened the packaging it will expand to a bike friendly size.