The Vac-u-Lock System is made and a patented by Doc Johnson. Vac-u-lock offers the ability to switch between different dildos, vibrating cocks, and penile extensions. Mix and match to your heart's content. The patented plug, made of high impact ABS plastic, holds the systems attachments firmly, without any chance of slippage or accidental removal from the harness system. The variety and versatility of the attachments is legendary:  from thick to thin, or long to short, it doesn't matter what you and your lover are in the mood for, Vac-u-lock delivers. Important note:  Vac-u-Lock dildos and Vac-u-Lock harness are only compatible with each other.