Don't matter if its a red or blue cap lamp both are identical just depends what year they were made.
PHILIPS 55W SOX PSG LAMP BLUE CAP . EXTRA LONG LIFE. NEW
PHILIPS 35W SOX LAMP PSG GETTER RED CAP NEW IN PACKET STREET LIGHT LANTERN
TRUHALO 55W SOX
PHILIPS 35W SOX 35w LAMP RED CAP sox35 SODIUM by22d (RRP £30)
25 X Philips 55W 55 Watt 840 cool white 4000k master colour PL-L 4pin
Philips SOX 35 W Pro BY22d
