This 51 head will not crack, break or melt under the extreme heat of a high voltage nickel-metal hydride battery pack, or under harsh hunting conditions. The bulb socket and switch assembly are molded to a higher standard than the regular 51 heads, which results in a tough dependable headlamp unlike any other. Choose between one with a direct stereo-style plug and one with no plug. BULB NOT INCLUDED. Nite Lite High Heat 5100 Style Headlamp With No Plug