My contractor had a heck of a time with this.  The 1/2" copper pipe would not fit into the area it needed to.  He had to install 1/2 in. Copper C x FPT Adapters to make it work.  Also, the cartridge itself did not work properly.  I had to buy an new cartridge and have submitted a payment reimbursement to Grohe.  Fingers crossed that I actually get reimbursed.  Overall, it is working great now.  Just had to jump through hoops to make it work properly.