The protrusion is 2.8 inches.
Pfister Model # BTB-D1YY is an 18" towel bar. 22" is the measurement of the entire length from wall flange to wall flange and 18" is the measurement of the bar alone.
Pfister does not have a matching Treviso double towel bar in the Velvet Aged Bronze at this time, however Pfister does make a Catalina double towel bar in the Velvet Aged Bronze finish. The unit is model #BTB-E5VV. For stock availability please check with your local Home Depot store. The store can also special order the product if it’s not in stock.