Replacement Foam Weatherstripping
A handy person from Tallahassee FL says:
March 10, 2013
Attached is a photo of the cross-section of the weatherstripping on the bottom of the lower sash of our windows. Although the photo does not clearly show it, the entire foam bubble was surrounded by white vinyl. The tab has two small fins on each side to secure it in the window groove.
Paul from SWISCO responded:
March 11, 2013