the speed at which water is ejected from the device or to an alternative attachment 22 as shown in fig5 the attachment 22 comprises a housing 23 in which a nozzle 24 is slidably mounted the nozzle 24 includes an outward facing shoulder 25 which in use cooperates with a corresponding shoulder 26 in the housing 23 to act as a stop for preventing the nozzle 24 from leaving the end of the housing 23 the nozzle 24 also includes a radial port 27 which leads into an intermediate chamber 28 defined between the nozzle 24 and casing 23 the end of the nozzle 24 is attached to a blade 29 and is sealed against the housing 23 by means of an 0 ring seal 30 upon firing the device water passes through the nozzle 24 causing the latter to slide along the housing 23 the direction of the flow of water until the shoulder 25 engages the shoulder 26 the impact of the shoulders 25 and 26 is cushioned by water which escapes into the chamber 28 through the port 27 the blade 29 pierces the casing of the target to allow the water to strike a fuse which would otherwise be protected by the casing but the interengagement of the shoulders 25 and 26 limits forward movement of the blade 29 and prevents the latter striking the fuse it will be appreciated that the.