Robelle 1106-12 Deluxe Winterizing Cover Blox for In-Ground Winter Pool Covers, 3-Feet, 12-Pack Cover Blox Measure 3 ft. long, 8 Inch wide and 4 Inch tall Replaces Your Standard Vinyl Water Tubes 16'x32' Rectangular Requires 32 Cover Blox 20'x40' Rectangular Requires 40 Cover Blox Convenient 12 pack