serves to urge the pin projections 12 into the locking recesses 9 of the bayonet slots 8 to secure the trimming device 1 against unintentional disconnection from the handle 2 the sleeve portion 7 and the plug part 11 form further electric contacts that cooperate to complete a circuit for the flow of electrical current between the battery in the handle and the trimming device the trimming device 1 includes a hood or shroud 15 which surrounds the plug part 11 for enclosing the male and female members of the bayonet coupling to preclude ingress of moisture to the electrical contacts the female member carries an annular seal 16 such as an o ring seal disposed in a peripheral groove provided on the sleeve portion 7 axially inwardly of the bayonet slots 8 and the shroud 15 has a close fit over the seal 16 to ensure a watertight connection between the shroud and the handle when the male and female coupling members are engaged the trimming device includes a drive unit 20 and a trimmer unit 21 the male coupling member 6 and the shroud 15 are provided on a housing 22 of the drive unit in which is housed an electric rotary motor 23 and a transmission mechanism 24 for converting rotary motion of a motor shaft 25 into reciprocation of a drive output.