Product Overview:

This double flipper smoke and acoustic seal has been designed for easy
fit onto both the stop and jamb on an internal doorset. Each seal is 2.1M
long.
When tested, this showed an unaided weighted sound reduction of
dB39. 

Fits to the stop and jamb independently
Allows easier fitting
Prevents misalignment and poor seals
Helps to achieve a sound reduction up-to 39dB