A market-leading innovator: Tristel is a leading developer of products for high-level disinfection of ultrasound probes and other semi-critical devices, with a growing presence in the hospital surface disinfection market. The company has a strong innovation ethos, leveraging its proven and validated chlorine dioxide chemistry expertise and product development know-how. Outperforming in device decontamination: In spite of lower medical procedure volumes during the Covid pandemic, direct sales of medical device decontamination products grew by 17% in FY20, driven mainly by EU demand. We expect Tristel to benefit as procedure volumes normalise over FY21-22e. Sustainable growth in surface disinfection: Many of the more rigorous decontamination procedures implemented in response to Covid are likely to be maintained over the longer term, supporting the take-up of Tristel’s new Cache range of user-friendly products for high-level surface disinfection. High and sustainable returns: Tristel is generating consistently high returns (FY15-20 CAGR in revenue, EPS and regular DPS of 16%, 17% and 15%, respectively). We believe the attractive return profile (ROCE >20%) is sustainable over the forecast period, improving further post US launch of Cache (FY22e) and Tristel Duo (FY23e). A “hidden gem” in the disinfection space: Our DCF-based valuation (7% discount rate, 1% TGR) implies a target price of 644p. In spite of high returns, Tristel is under-owned by mainstream investors – we initiate with a Buy.