I believe (but I could be incorrect) that this model is in general limited to the IWC bracelet / IWC rubber strap designed for it.
The design of the lugs preclude the attachment of standard bracelets or straps (there are modifications available - for example http://www.iwc.com/forum/en/discussion/23789/)
While it is expensive (GBP900+), I have found the IWC bracelet to be of excellent design and comfort. It also gives the watch a whole new character.