PVC/CPVC/PE nipples furnished may be produced from extruded stock, or from molding grade PVC/CPVC compounds. Both processes provide quality products meeting ASTM requirements. Spears® thermoplastic nipples are produced in a variety of styles, several of which are illustrated below. These are referred to as Plain (no threads), TOE (Threaded One End), TBE (Threaded Both Ends), Grooved (which can be Plain x Groove, Groove x Thread, & Groove x Groove). Special varieties of polyethylene nipples include Cut-off, Four-In-One Cut-off and Four-In-One Cut-off Reducing. Close nipples are simply two (2) threads back to back. Short nipples is a term commonly used to designate a slightly longer nipple that is usually the smallest length above ''close''. The following table shows length of close and short nipples.