Vac-u-Lock Strap-on Sets - Our No.1 range of complete Strap-on Kits from Doc Johnson.  The Vac u Lock Strap-ons have been designed with a special non slip system and will fit up to waist 44".  The Vac-u-Lock Strapon is used by some of the World's most famous Porn Stars and for very good reason. They offer extreme quality as well as being adaptable, allowing a variety of dildos/dongs to be interchanged with them.