With its understated simplicity, the HMS1 line is a modern take on Arnold & Son's traditionally elegant design combined with superior craftsmanship. Housed in a classically styled 40 mm case with see-through back, the hand-wound A&S1001 calibre is manufactured in-house and decorated with either straight or radiating (rayonnantes) Côtes de Genève guilloche. The movement is 2.7 mm in thickness with twin barrels generate a minimum power reserve of 90 hours and a more constant force, hence greater accuracy the whole time the movement is running.