They can be made of metal and rubber or just rubber or soft foam and fabric the kind you choose will depend on the type of door you re dealing with.
Soundproofing tape door.
White doors windows insulation tape 2 rolls 1 2 inch wide x 1 4 inch thick foam weather stripping gasket tape seal for draft soundproofing total 30 feet long 2 x 15 ft each 4 8 out of 5 stars 14 11 98 11.
Door insulation and soundproofing tape 2 rolls 3 4 inch wide x 3 8 inch thick foam draft gasket tape 10mm thick and black total 13 feet long 2 x 6 5 ft each 4 4 out of 5 stars 3 403 15 98 15.
If you are willing to change your doorframe to a metal one then this is a very effective door sealing method which will make a huge difference to the sound resistance of your door.
Generally you should stick with the pillowy kind if you re soundproofing interior doors and rubber sweeps for exterior ones.
Soundproof door sweeps are items you attach to the bottom of your door to bridge the gap between it and the floor.