These adapters are 2 inch NPT MALE to 2 inch PVC Hose (2" x 2"). They are manufactured from corrosion resistant 304 SS (Stainless Steel). Tapered threads such as these should always be assembled with thread sealant or pipe tape to ensure a vacuum tight seal. PVC hose can be connected to this adapter with a hose clamp.
Commonly available PTFE pipe can be used for dry connections. However, Ideal Vacuum Products recommends the use of nickel coated PTFE sealing tape when connecting NPT Stainless Steel fittings in order to avoid thread seizing.