| On the UK Flash car cleaner there is an indicator on the side of the filter which is visible through a cut out in the side of the unit,apparently it turns from black to brown or visa versa when in use to tell you that it has come to the end of its use.The filter that came with the kit is only good for three uses,i didn't notice the indicator change colour on mine but did notice that the windows on my car were showing white streaky marks which i took to mean that the filter was on its way out,i bought a replacement filter which cost £4.95 but it is for 10 uses..oh and some more shampoo which is a 600ml bottle for £3.95 | 
