Compare bases and harness compatibility
Measure the attachment before buying a toy for an existing harness.
Check the ring and retaining base
A broad base and an attachment that stays seated are separate from shaft length. Compare the maker’s stated O-ring size, shaft diameter where it meets the base, and base shape. Check the harness comparison for examples of how harness fittings differ.
Check surface requirements
A suction base generally needs a smooth surface as specified by its maker. It serves a different purpose from a harness ring. A product labeled harness compatible can still require a particular fitting or size.
Look for the intended use
For anal use, look for a purpose-designed flared base that prevents the toy slipping inside. Do not infer suitability from compact size or a photo of the base. Planned Parenthood’s sex toy guide explains the role of a flared base.