You are buying 1 (ONE) NEW 1" SQUARE by 18" LONG TUBE of CLEAR EXTRUDED ACRYLIC. (One inch outside dimension by Eighteen inch long) These tubes have a 1/16" thick wall which provides an outside dimension (OD) of 1" and an inside dimension (ID) of 7/8". The sides of the tube tend to be very slightly concave. This is the nature of extruded square acrylic tubes. The picture shows one square tube for representation of our product and you are buying and will receive ONE 1" OD x 7/8" ID x 18" square tube. To assure that you get the finest quality, the protective sleeve is kept in place on the tubes while being cut to protect the acrylic. All tubes ship with the original protective paper sleeve as seen in the pictures. All tubes have saw cut edges on both ends which might cause micro chips as seen in the pictures. Please allow a tolerance of +/- 1/16" on all pieces.