I have a Dolphin Premier robot cleaner that is over three years old now. I've pretty much used the cartridge screens most times for cleaning the pool and have replaced the filters once. I had only recently noticed the upright sections that hold the filters had started loosening and when I took the cleaner out of the pool it allowed a lot of debris back into the water. Upon a closer look, the little tabs that hold the upright pieces had almost all broken, letting some of the dirt and sediment the cleaner had sucked up to slip back out of the cleaner. I found the best price for the cartridge replacement at Sunplay and ordered it. It arrived quickly, and works and fits fine in my Premier. The cartridge and filters are the same length as the old unit, but around an inch shorter in height. That's unfortunate since I had hoped to use my old filters on the new cartridge since they still had life in them, but no matter, the new ones work well and my issue with dirt escaping back into the pool is gone. All in all, I'm very happy that I got this.