Hi guys,
At this point I have rail from a variety of manufacturers. My track is nickel silver code 250 and 215. I also have a variety of rail joiners, but now mostly Split Jaw. Nothing else works as well! Last month I ordered a couple of their expansion rail sections and they were sent to me right away. When I finished construction last month, I was out of Split Jaw clamps. I ordered another dozen and they arrived yesterday, less than a week after ordered. Great product, and great service! And no, this is not a paid endorsement. 
Cheers,
Matt