Convenient and completely portable, the Direct Plug-in will fit all Welch Allyn 3.5v instrument heads, is rechargeable, durable, and easy to use. Features Built-in AC adapter with prongs enables convenient recharging wherever your practice takes you - a completely portable power handle! Well-balanced and rests comfortably in the hand. Weight is evenly distributed end to end. Adjustable rheostat controls light intensity. Long-lasting rechargeable nickel-cadmium battery included. Smooth, non-abrasive knurled finish ensures a no-slip grip. Chrome-plated brass constuction provides durable and reliable long-life. Positive "off" rheostat makes it impossible to turn power on accidentally. Permanent connection for instrument heads assures permanent, snug fit. Nylon rheostat control cap designed for finger-tip control.