
IPL devices, such as the SmoothCool HR/SR, convert light energy to heat energy to treat unwanted hair and skin pigments. IPL devices can use photothermolysis to remove unwanted hair, correct skin issues like age
spots or rosacea. Treatment with an IPL device affords the treatment provider a
greater wavelength spectrum than standard lasers.
Unlike other types of hair removal that use just a single light wavelength, IPL devices use a full spectrum of light wavelengths. This allows treatment of larger skin portions at a time so that areas such as the legs or back can be treated in a fraction of the time it takes standard lasers for hair removal. IPL devices also can alter the light beam intensity on the fly with various filters, which helps clear up complexions and improve skin texture.

According to the Society for Clinical and Medical Hair Removal, IPL, such as SmoothCool HR/SR, which are FDA approved for permanent hair reduction, are a far more practical option for the treatment of large areas like the back or legs, where the painstaking process of electrolysis would simply be too painful, pricey, and time consuming for most people to endure.
Many clinics that offer the Hair Reduction procedure do guarantee two years of customer satisfaction for patients who complete their minimum number of required sessions (usually in the ballpark of 3-6). When hair does regrow, it'll be thinner and in less quantity, regardless if it was a chest hair treatment or a bikini line treatment. When you consider all the time, money, and pain you'll save yourself over the course of two full years without shaving or waxing, permanent hair "reduction" sounds all the more appealing¹.
1Hair Removal Forum Newsletter / May 2008, "A Primer on Permanent Hair Removal"