This is a 16 ounce bottle of Rainbow Solution OTO 1 which is a replacement used for Chlorine testing in Rainbow Kits 78HR (All-in-One), 78DPD, 752 (2-in-1) and 756. The 16 ounce bottle is a larger size than what is included in the kits. Larger size bottles are economical and convenient if you are using a lot of reagent.








