I have just looked at the filter in detail. Unfortunately, this is not apparent in any way. Based on my experience with it, I would now guess TK-A (For general air filtration, odours, kitchen exhaust air, solvent vapours, welding fumes, diesel odours), hardly TK-B. Much more likely, however, no classification at all. An odour reduction for cooking odours, smoke flavour (oven) is clearly "smellable" over approx. 1/2h according to my perception.