High density and self stick. Compressible to fill gaps on windows & doors. Can also be used as a seal around air conditioners. As a refrigerator/freezer door gasket. To prevent rattles, squeaks & vibrations on cars & trucks.
It can reduce the sound and light coming through my bedroom door. Can be used line the inside of the door frame as well as the top portion.

The sealer is fairly thick and compresses really well when the door is closed making almost and air tight seal to prevent sound from traveling through the cracks. 

Usage:
1.Measure the gap you are trying to seal and then find the appropriate width/height. Plan to attach the seal to the appropriate part of the area you want to seal 
2.CLEAN the surface vigorously with rubbing alcohol and a cotton ball (or a microfiber cloth if you have a smooth surface). Allow the alcohol to dry and then inspect the surface, if it is glossy or coated you may have to use a fine sand paper to ensure the adhesive can attach. 
3.Stick the weatherseal and slightly pull as you apply. This seems to allow the weatherseal some room to expand without sloughing off or bunching. 

Various colors and sizes are available