For Smart-valves' top or bottom floats.
Clear - for all top and bottom floats except Mk2 bottom.
For Smart-valve Mk2 (black) bottom floats, please select replacement bottom float (Mk3i - https://www.gardensmartshop.com.au/products/smart-valve-mk3i-bottom-float/) as they have an adjustable grub screw for silicon placement. Earlier yellow silicon for Mk2 bottom float no longer available.