The antimicrobial travel cap helps keep the brush head clean while travelling.The inside of the cap (where the brush head goes) is treated with an antimicrobial additive, which is made from a specially formulated silver compound. The compound is integrated into the plastic, as opposed to a coating on the surface – this makes it very stable and durable.Up to 99.5% of bacteria is killed after 2 hours of contact with the treated surface, reducing bacteria buildup on the inside of the travel cap, making for a more hygienic travel solution.For general guidance on hygiene, it's important that you rinse and dry the brush head after brushing.