Anyone heard of these? They say made for certain systems, but I wonder if they'll fit any three-inch chlorinator.

ACCU-TABS BLUE 55 LB. BUCKET
PPG Accu-Tabs Blue 55 lb. Bucket *
* Accu-Tab three-inch blue calcium hypochlorite tablets are easy to handle and store. They are made specifically for the Accu-tab chlorinating systems. Tablets contain no stabilizer (cyanuric acid) and, therefore, do no contribute to stabilizer buildup.