I don't know if this is old news or not, but PetSmart sells a mini mag float that is just under 2 inches long and about 1 inch wide. This is NOT their small size, but their mini. Safe for glass and acrylic. Model Float-25A
It isn't where they keep the other mag floats, but on the end of one of the isles. It was 7.99
Thought this might be of interest to someone.