Mag Float 510 Extra Large Acrylic Aquarium Cleaner - Bulk Reef Supply
F-2 for 1/4″ to 1/2″ – Mighty Magnet Inc.
Mighty Magnet Inc. – Clearly the best
New Hampshire - :Mighty Magnet F4 model in original Case with pad, etc for thick tanks. Hard to find these used | REEF2REEF Saltwater and Reef Aquarium Forum