Technical description: Silver-plated brass. 'Catholic fingering' (1st valve semitone, 2nd valve two semitones). With two parallel water-keys. No fitting for music card-holder. Valve type: 3 Périnet valves, top-sprung, alignment by three-armed washer under the spring engaging with slots in the inside of the valve casing. Repair History: The A♭ crook is an unplated replacement from a different instrument.