The Pro X Series Quick-Connect Fat Sacs have raised the bar in boat weighting systems. Similar to river rafting material, the new Valmex material is so strong that punctures and abrasions are virtually a thing of the past. Tough strong seams are welded and taped to prevent common failures. The new quick-connect valve system lets you pump water 10 times faster than the old water bed system. Pro X Fat Sacs are available in plenty of sizes and shapes. Sold individually. New quick-connect valve system Pumps water 10 times faster | Pro X Series V-Drive Sac - 16" x 16" x 42", 400 lbs in Black