ebay item number :
270233637675 (put it in search box )
i've got one. it's brill.
plunger that powers blocks away.
fill bath/sink a couple of inches (plug in when you have shower? ) hold end under water ,suck up water then blast it down plug hole and push pull handle a couple off times. repeat a couple of times , job done . thirty seconds.
as the vicar said, cover the over flow 'coz it's linked to the plug hole and you wouldn't want a face full of nasties would you?