This prefilled container fits inside the Mineral Chamber, which is in the FROG Pool Tender Cycler and makes handling chlorine much easier. No more measuring out the right amount, touching chlorine tablets or accidental spills that can bleach clothes. Just pop off the top, insert into the Chamber and set the dial for the precise 0.5 to 1.0 ppm chlorine level. A chart in our handy manual will help you with that. The erosion design wets a small amount of chlorine at one time so it’s easy to precisely meter exactly what you need. Replace chlorine chamber when empty (approximately every 2 to 3 weeks depending on your usage.