C.P.R. Drain Shield is the newest innovation for insuring your planter is draining properly, avoiding root rot!C.P.R. stands forContained Plant Respirator. Simply pop it in the bottom of your planter over the drain hole and add potting mix. The multiple passage ways make sure water gets out in a controlled way and that the root system gets the oxygen it needs for optimal planthealth. When used with Korestone saucer the drain hole is open for maximum drainage and air circulation.