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-on's, Heart Strap-on, Latigo Leather Strap-on, Bare As You Dare Strap-on, Vibrating Leather Strap-on, Beginner's 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: Seamless 1.5” (3.8cm), 1.75” (4.5cm), and 2” (5cm) welded nickel free metal sized rings .