Further Information:
Principle: Open
Coupling to the ear: Supra-aural
Impedance: 2000 ohms
Rated power: 0.1 watts
Pressure force: 2.5 N
Frequency range: 16 - 20,000 Hz (-3db)
Distortion factor: <1%
Sound pressure: 94 db at 1 mW
Plug: 6.3mm Jack plug
Cable Length: Approx. 3m
https://www.thomann.de/gb/sennheiser_hd424_ohrpolster.htm?shp=eyJjb3VudHJ5IjoiZ2IiLCJjdXJyZW5jeSI6NCwibGFuZ3VhZ2UiOjJ9&reload=1
https://www.amazon.de/Ohrpolster-f%C3%BCr-Sennheiser-424-Kopfh%C3%B6rer-Gelb/dp/B000EULJPQ
https://en-us.sennheiser.com/accessories-hd-424-ear-cushion
https://www.musicstore.com/en_US/USD/Sennheiser-Ear-Pads-for-HD-424/art-ACC0002163-000
https://www.headfonia.com/sennheiser-hd410-hd414-hd424/2/
https://www.tonepublications.com/old-school/sennheiser-hd-414-and-424/
https://forums.stevehoffman.tv/threads/something-old-but-new-the-sennheiser-hd-424.694159/
https://www.head-fi.org/threads/hd424-nice-vintage-cans.118499/
https://www.hifiengine.com/manual_library/sennheiser/hd-424.shtml
https://www.manualslib.com/manual/345483/Sennheiser-Hd-424.html?page=2#manual
Any questions, feel free to ask.