Vac-U-Lock Modular System Thin 7″ Natural Dong. Doc Johnson introduces a perfect addition to your Vac-U-Lock collection. The 7″ Thin Natural Dong combined with Doc Johnson’s most popular state-of-the-art strap-on system. Fasten your seat belt! You are in for a ride! White flesh colored 7 inch vinyl rubber dong that is designed as an attachment to the Vac-U-Lock group of toys. Made using phthalate free, non-toxic materials PVC. Recommended lubricants are water base. Details: Circumference 5.03 inches.Dimensions 7.30 inches long, 1.60 inches wide, 2.10 deep. Insertable length 5.80 inches. Vac-U-Lock Modular Sex System Attachment from Doc Johnson Novelties the Great American Toy Company. New image added May 22, 2013. Please note the packaging has changed on the Vac-U-Lock Sex System. -old yellow, gold box.