The Series 4 is based on Paxman's highly successful Series 3 and shares many of its characteristics. It also incorporates several features usually reserved for top level professional instruments. These include a detachable bell as standard, water key on the mouthpipe, protective nickel hand guard and nickel silver valve casings. The bell is medium large bore, the optimum for this type of instrument, made in yellow brass for a characteristic warm, yet exciting sound. The wrap is based on a Geyer style, which makes it a particularly free blowing horn. The left hand position is adjustable by means of a movable thumb lever and adjustable finger hook, to make it suitable for the younger player or adult.