Spare cassette waste tank suit the Left hand C400 series of thetford toilet. If unsure if its left or right, check location of the small green valve knob in the photo.
These are GENUINE THETFORD replacements. They are not aftermarket reproductions.
Take care, there are a number of different cassettes available, check the specifications and photo.
We have been selling this product for several years now. We usually stock at least a couple of these. If you order more than the 6 we have in stock, the delay is around 6 days to get more.