A cast aluminum base for mounting air terminals to the top of horizontal pipes or railings where conductor is not required up to 2 in. (5.1 cm) OD. Stainless steel U-bolt, nuts and washers. 3-1/4 x 3-1/2 x 1-1/2 in. (8.3 x 8.9 x 3.8 cm); approximately 5.5 oz. (156 g). Use suffix 1/2 and 5/8 inch to denote air terminal thread size.