21 X 28 INCH PEBBLE MILL Stock Number: C-1035 Mfg. Patterson Industries 21 inch diameter x 28 inch wide 40 gallon capacity Porcelain/ceramic lined, dust cover. 1.5 Hp, 1725 rpm, 3ph 8,5 x 11.75 inch top port (1) available Posted in Process Grinders and Mills.