Physical description
Black and White photograph (montage) of nine type of trolley poles spring bases used by the MMTB, c1970. Provides photos of US6, US13, US15, English Electric, Ohio Brass, US 15 Converted, MV, MMTB and PCC types. Titled "Trolley Pole Bases"
2nd copy added from donation of Geoff Warburton 7/10/17.
3rd copy added 11/6/2022 from unknown source
Inscriptions & markings
2nd copy in pencil on top edge "Trolley pole bases MMTB"