We made this gray silicone rubber bulb seal to fit in the extrusion on the hingeless (removable) baggage compartment doors on Airstreams in the late 1960s. On those hatch doors, the T-base slides into a channel on the back side of the doors. This seal is included free when you buy the extrusions to build a new door but we're making it available separately, too.
Bulb is approximately .16" diameter and T base is also approximately .16" wide.
Let us know if you find other applications for it.
Sold by the foot. Assembled door show for context only.