Unfortunately we have sold out of all our X2 Digital Wireless inventory in 2011 now.
One option is to find someone selling an XDT4 or XDT4 spare parts on eBay or independently at this point.
The other option is to try and attach it to your guitar strap with tape, glue, or some other means.
I don't use the metal clips at all myself on either one of my systems. I bought a pouch from Musicians Friend they have just to hold transmitters like this It loops right around my guitar strap no problem. It was about $10 I think. Those metal clips they came with didn't look trustworthy to me.