St John Ambulance Medium Dressing 120 x 120mm Each F90106. Highly absorbent pad cushions wound and protects against infection. Supplied in sterile plastic wrapping.. This sterile St John Ambulance medium first aid dressing has a highly absorbent pad, which is designed to cushion the wound and provide protection from infection. Ideal for refilling first aid kits, this medium dressing measures 120 x 120mm and is supplied in a sterile plastic wrapping.