That's the type that was probably originally supplied with the unit, which has since been de-rated to 50V if accessible, superseded by the Bulgin PX0430/SE for mains applications (has strain relief and needs a tool to open rather than just unscrewing by hand.) and not much dearer, e.g.:
http://cpc.farnell.com/bulgin/px0430...5116?st=bulgin