Bought one of these a few weeks back when it was £20 and appears to be working OK, I've not noticed any lime scale build up in my kettle since using this.
This has been posted on here a few times and the cheapest I've seen so far has been £17 but hasn't been that price since for some time.
* Designed to fit into fridge door
* Cartridge replacement indicator
* Easy pour through lid
* Total capacity 2.5 litres
* Includes 6 x Aqua Optima Double Life 60-day water filters
* Height: 26 cm, Depth/Length: 11 cm, Width: 26 cm