They are indeed the Schumacher ones, still available from anywhere. I believe the part# is U744 but will try to look out the header card to confirm. The plastic 4 cell strap is very good on the X5, but I prefer the Schumacher one on the 2 cell side, then put the other one purely to match.
I have seen people make up almost factory looking straps from other things, see here for ideas
http://eraprise.com/4wdrcbb/viewtopi...8f312c0a73c9f0
Dan