ESP's Stainless Steel Liners are made of 304 Stainless Steel. A standard in the environmental sampling industry. 304SS has a minimum of 18% Chromium(Cr) and 8% Nickel(Ni) providing high corrosion resistance and at the same time durable liners to protect your samples. Find the corresponding 2" Liner Caps here. 3" Teflon Squares and Arlon Self-Fusing Tape here..035" Wall Thickness