Magnetic assembly for a controller for use in a wet environment

A magnetic assembly for use with a controller in a wet environment, the assembly comprising at least one magnet 3a,b fixed to a holder 2. Also claimed is the controller (Figs 2, 4-6) and fluid delivery system for use in a wet environment e.g. temperature and flow of a shower, including a housing 1 defining a sealed waterproof internal volume 5, the magnet holder with magnet(s) moveable relative to the housing, a plurality of sensors, preferably Hall effect sensors 4a-4o, greater than the number of magnets, fixed relative to the housing and located within the sealed internal volume, suitable for detecting the relative position of the magnet(s) and outputting a signal. The magnet holder may be a rotatable annular bezel, ring or dial 2 removably attached to the housing by an annular retainer 6 with resilient biased tabs 61 urging interlocking projections 62 into circumferential groove 11 on housing. The projections and groove act as a bearing allowing bezel rotation. Two magnets may be located on the bezel, the distance between magnets is less than the distance between sensors equidistantly located in a circle within the housing.