Hello dear friends! Today I bought from Lidl coal filter for the filter system during cooking. These filter mats can be used well for the internal filter. Old filter out- filter mat from the frame- to cut new coal filter- to insert inside old frame or fix with double sided adhesive side -ready! Reinstall and very expensive artificial. This costs a maximum of € 2,50. Thus this alternative is better than what you have to pay with an internal filter with coal, namely over € 19. Also Sparkel1 has the same opinion! Many greetings from Torsten