1/2" heater hose spring clamps are to loose

I thought that the heater hose were 5/8"

Will anyway, I use the Gates Power Gripe heat shrink bands
For the heater I use #32924 15/16" to 1 1/16" range or,
#32922 is 15/16" to 13/16"
What is the OD of the hose you are using?