These O-rings can be used with any flared base dildos on an interchangeable O-ring harness. Use with Sportsheets Plus Strap-ons, Vibrating Black or Purple Velvet Strap-ons, Vibrating Black or Purple Corsette Strap-ons, Heart Strap-on, Latigo Leather Strap-on, Bare As You Dare Strap-on, Vibrating Leather Strap-on, Beginners Pink Strap-on and Dildo Set, Simply Sexy Strap-on, and the Divine Diva Strap-on. Works with all the Sportsheets Flared Base Dildos. Includes: 1.5 inch (3.8cm), 1.75 inch (4.5cm), 2 inch (5cm) welded nickel free metal sized rings.