Its an EJ three speed,fitted to many lightweights of the era.It will have a single plate clutch of very simple design.These boxes have no bushing between the mainshaft and sprocket gear,in common with the super h/wt Sturmey fitted to some SS100s.Internally,the box is a near exact copy in miniture of the Sturmey Archer LS box,and quite well made[IMHO].Incidentally ,an exact copy of this box was made in Australia by the Diecut sprocket company,but completely bare of any markings.Usually exposed to a maximum of abuse along with the Villiers motor by the persons who typically owned these cheap bikes.Regards John.