Jim-
How much do you need? I've got a spool of the stuff in 1/4 inch which, as you know, expands to accommodate a larger wire bundle.
Regards,
Stan
(This stuff was created and patented by AMP Incorporated (now TYCO Electronics) and went by the trademark SPIRAP. I believe they sold the rights to T&B. It's usually found in various diameters in both black and white at electronics distributors.)