by Fred Stoermer
The brand name is 'RECMAR', and I get it at Boater's World which is a discount marine supply chain.
RECMAR's name for this particular product line is 'SLIDE-RIGHT CURTAIN TRACK'. You can buy just the sliders in a bag, or a kit including track and mounting screws plus the sliders and stop screws for the ends of the track sections. The track is identical to the plastic track above the front doors on my 1970 Westy Campmobile, and the sliders fit perfectly in those Westy tracks plus the aluminum track above the sliding side door.
The sliders are individual plastic pieces with loops for sewing onto the curtains. The original Westy curtains had a length of fabric with the sliders already attached, and this was then sewn to the top edge of the curtains. I sewed the RECMAR sliders onto the curtains my wife made for the Westy and it went very quickly even with my clumsy efforts.
I have an unopened track kit here now. It has 2 pieces of track, 36 inches each, plus a bag of sliders and all the hardware. The price at Boater's World was a whopping $6.99. Kits are also available with 24", 48", and 60" track sections. The packaging even includes instructions for making the curtains.
I can't find an address for RECMAR on this package, but they market this stuff for van conversions and RVs as well so it should be available just about anywhere.