3 1/4 X 12 DUCT 100 LONG Hercules manufactured snaplock duct is cross broken and is shipped Lshaped (2 pieces per joint). Sizes range from 3.25 x 10 wall stack all the way up to 20 x 20 and most are available in 4 5 and 8 foot lengths. End caps elbows and transitions are also available.