Don't wash the pen cap with the washing machine, it will deform, so it's better to wash it by hand.

Cleaning method: first soak the pen cap in clear water for ten minutes, then gently scrub it with a soft brush dipped in soap or soap, as well as the tongue. Note that the hat touches the edge of the head. It gets dirty easily. You can apply some soap and then scrub it carefully with a soft brush. After brushing your teeth, soak in clear water, wash off the soap and dry it.