Ignition transformer for some Belling gas/electric appliances. Please note the early version (white) has been replaced by the black transformer:
BELLING: B900DFWNG/LP, BG900DFSSNG/LP, BG900DFWNG/LP, BR54DFB, BR54DFC, BR54DFR, BR54DFW, FSDF60DOS, FSDF61DOWCS