UltraFire CREE XP-L V5 26.5mm 1200lm 5-Mode 3.7V~4.8V Flashlight Torch LED Blub Reflector for UltraFire WF-501B / 502B It is newest Cree led blub So this Cree XP-L V5 led blub is brighter than Cree XM-L t6 lamp beads fit for ultrafire 501B, 502B, 503B, 504B led blub and G60, G90, G120 fit for Surefire 6P, 6Z, 9P, 9Z, Z2, Z3... This is a one size fits most bulb