Denicotea 10 piece crystal filters includes ten replacement filters for your Denicotea cigarette holder. These filters use a silica gel that has a highly porous structure which reduces tar and nicotine from tobacco smoke. The used filters will change color from clear white to dark brown illustrating the effect of the tar and nicotine reduction, and also indicates that the filter has to be changed. Only the original Denicotea filter has the red cap! Denicotea filters intended for use in denicotea holders, not for use in tobacco pipes.