Property now already the fourth cartridge of this type ausgetautscht in my house, all were or are Grohe original parts, the older were white, the new ones are blue, in the quality but there is no difference: all begin sometime to squeak and then remain stuck, so you can not turn off the water. It seems only a matter of time to be, it can daueren 3 years, or go very fast. The last one has ever held just one day - this is a company like Grohe, about which one high quality accustomed unworthy. It may be that the problem is due to the chalky water we have in our area, but other fittings get away with it for decades cope.
