We provide high quality and very versatile lights. They contain high intensity and high quality LEDs rated to last between 75,000 - 100,000 hours. These lights will start the "Tuffleye" material curing in 2 seconds and completely cure it in about 10-20 seconds. They have been engineered and made specifically by Wet A Hook Technologies. The AC/DC model is capable of running on either 3AAA batteries or an AC current with the adaptor included. The AC adaptor is able to self adjust an electric current from either 120 or 240 volts. Making International tiers happy. (Caution: The use of any other AC adaptor may burn out the LED) We have also added micro circuitry that will notify the user of the intensity of the DC current. When there is not enough battery power to adequately cure the Tuffleye material, a red light will appear. This will notify you to either place fresh batteries or move to an AC power source. The smaller Penlight uses 3AAA batteries only. Even though the TuffleyeTM light uses the same technology as has been used in the medical and dental professions with safety for over 50 years, we advise the use of the light shield provided and discourage users from looking at the direct light.