Wipac Replica Rear Lamp, for use on BSA models: BSA Bantam D7, D10, D14, B175, C10L. Triumph models: T20B Super Cub. Ariel Colt models, AJS/Matchless lightweights, Francis Barnett, as well as Sunbeam models.
This rear lamp was also known as Series 143 and Series 143b, when the unit was fitted with a stop and tail lamp in the mid 1960's, under part number S3611. 
OEM: S0088 / S3611 / 143 / 19-0166 / 19-0108