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.