Why don't you have a quick google before making stupid comments?
I've tried the one from john hewitt & collins water products...whilst doing the job and working 'ok', neither have been as good as this: http://www.purefreedom.co.uk/24v-aquatec-reverse-osmosis-booster-pump-power-supply-p-274.html?page=2(Collins are decent and i'd recommend to anyone in regards to membranes & prefilters though)I have it on the pipe in-between my last prefilter & first membrane