1.75" Fiberglass Mortar Tubes 50ct Case Tube Length - 12.5" Tube Inner Diameter - 1.75" Set of 50 Fiberglass Mortar Tubes (Plugged) No Base DO NOT USE If your shells are smaller than 1.75" Firing too small of a shell from too large a tube can cause a low-break, possibly causing personal injury or fires being started.