For the Neakasa M1 litter tray, there is no specific mention of a carbon filter in the available sources. However, if your model includes a carbon filter, here is some general information:

- Generally, charcoal filters in litter trays need to be changed periodically to maintain their effectiveness.
- You can通常 purchase these filters from the manufacturer's official website, online shops that sell the product, or pet specialty shops.

If you need specific confirmation for the Neakasa M1, it is recommended that you consult the instruction manual or contact Neakasa customer service directly.