Been looking for one of these for some time. Popped into my local Robert days and saw this. Cheapest price I've seen. Online these retail for about £11.99.
You get the bottle and 4 filter discs.
If your on the move a lot these are ideal as they hold 0.6 litres of water.
The filters purify tap water (if you live in a area where your water is cloudy or has quite a high co substrate of chlorine these are fab