Splash Paks are water resistant which means that water will bead up on the pak and they will dry out quickly, great to use with water proof pumps or for a day at the amusement park where water rides may get you wet. These are not water proof due to the stitching and the zipper 'Double Zip' adds a new dimension to pumping! The double zipper allows you to decide which side tubing will extend from.Standard size Pump cases measure approx. 3 inches wide by 2 1/2 inches high. They hold all pumps except for the distronic d-tron pump which is larger than standard size pumps. D-Tron Size is also available in this style.