P422 Brake Blocks - Interchangeability?

[Al T]

I think I've got P422 brake blocks on my Cannondale Synapse Claris (Tektro Calipers)...for spares have I got to buy brake blocks labelled as P422 or are other types / brands interchangeable off the likes of ebay etc?
They say the only daft question is the one you dont ask...!!
Thanks in advance...
Al.