Slide in Window Weatherstrip used primarily in Metal and Vinyl products.
T-Back Slides into slot Assorted Backings Widths.

The weatherstripping I have is a.187 t-slot. However, the foam bulb is closer to 3/8 inch or.375 diameter. In addition it appears an angled piece comes off the picture you posted, versus no angular piece on my weather stripping? This is a foam-filled bulb seal weatherstrip for T-slot applications. This weatherstripping provides superior weatherability and chemical resistance and is designed to be low friction. This weatherstripping is sold in 24ft lengths. Used in aluminum or vinyl windows at the top and bottom of single or double hung design. T-Slots are used in aluminum or vinyl windows, used as a frame or sash seal in casement windows, or on the meeting rail of double and single hung windows.

Weatherstrip,.250 Offset T-Slot Slide-On - White or tan Window Offset Bulb Weatherstrip. Slide in T-slot 5/16 Hollow Bulb,.312. Weatherstrip 63-465W T-Slot Bulb Foam filled White bubble seal. Priced by the foot and sold in multiples of 100 feet.see more. T-Slot Bulb Foam filled White bubble seal. Priced by the foot and sold in multiples of 100 feet.

.275 T-Slot Backing, .375 Foam Seal

1,000' Roll .275 T-Slot Backing, .375 Foam Seal

T Slot Weatherstripping

T Slot Door Seal