Abstract: A boot assembly for preventing ingress of dirt into one end of a bore in a housing in which a piston works usually consists of a first portion sealing against the housing adjacent to the end of the bore, a second portion sealing against the piston and a flexible web connecting the two. To prevent the second portion lifting away from the piston, to which it is conventionally attached by being stretched round a groove at the end of the piston, the boot assembly is combined with a plate, having its outer peripheral edge sealingly connected to the second portion, and an inner face in abutment with the adjacent end of the piston.