Cressi 5mm Ultraspan Boots Info Cressi Ultraspan 5mm Scuba Diving and Wetsuit Boots are a superb non-zipped, pull on boot made from Cressi-Sub's ultra stretchy Ultraspan 5mm neoprene. Excellent for scuba diving and for general watersports with a rugged sole and reinforced areas on the heel and upper foot. Cressi 5mm Ultraspan Boots Features Non-zipped pull on boot. Rugged sole for protection. 5mm Ultratretch Neoprene. Fin strap stopper.