I've tried the AW IMR 18650 high drain, the AW Protected 18650 2600mah, the grey ultrafire protected and the Red 3000mah Protected Ultra fire as well as two Tenergy Cr123 3.0volts and they all fit.
which grey ultrafires?
they are prob. slight different sizes. (I've seen ultrafire do this before)
DealExtreme: $9.93 Ultrafire 3.7V 2400mAh LC 18650 Protected Battery 2-Pack
$9.93
DealExtreme: $7.44 UltraFire Protected 18650 3.7V 2400mAh Lithium Batteries (2-Pack Grey)
$7.44