These are the same disposable liners used in collection kits, these are 36 inch extra soft and clear polyethylene. The Colorado model has a center taper end. These clear liners work with any length Colorado AVs.
A.V. collection liners are available in either Colorado or Missouri style. The two differ from each other in the tapered end, the Colorado model having a center taper and the Missouri having an edge, or side taper.
Many breeders like to assemble their own kits, mix and match components, or reuse certain components, so they'll get their supplies separately. Semen collection coponents range from filters to liners to bottles.