Pumpin' Pal Collar Rings for silicone X-Small and Small flanges are a pair of spare Hard Plastic Adapter for Small and X-Small Silicone Flanges only. These are not needed for the Medium, Large, or X-Large Pumpin' Pal flanges. These are not Spectra adapters. Our XS & Small Pumpin Pal Silicone Flanges are all sold with a pair of theses Collar Rings. You would only need these if you'd like a spare set or lose yours. Save $ and order along with the Pumpin' Pal Flanges & Spectra Connectors.