This is my first chemical feeder having always done it by hand. This unit has a "see through" compartment that holds several 3" chlorine tablets. Other reviewers have commented that this was a desirable feature and I tend to agree although I am sceptical of how well this is going to weather and stay "see through".This unit is well constructed with a easy to open top cover where the tablets get inserted. Standard arrangement woith a rubber "O" Ring to seal the cap to the chamber and silicone grease is supplied to keep the "O" Ring lubed.This has been installed and in service for a little over two weeks and seems to work well, keeping the chlorine level in the pool constant. I will make an addendum to this review after several months of use to update.Botton line;Same price as comparable units and has the "see through" design so you can easily tell when new chemiocal is to be added.Easy install. If you can work with plastic pipe and glue, this is a snap.Greta instruction manual.I would make this purchase again.