These corrosion-proof 18" PVC 90° Elbows are for the construction of exhaust ventilation systems. PVC material compounds used in the manufacture of these duct fittings conform to PVC 1120, ASTM D-1784, Type 1, Grade 1, Cell Class 12454-B. These elbows are a three piece design which is considered standard and are furnished with a centerline radius approximately 1-1/2 times the duct diameter. Centerline to end is 19.062" and socket depth is 2.5". Service temperature is 33°F to 140°F. NOTES: Fittings are triple bead welded. Pictures are to represent style of fittings only; color is gray.