Red dot laser head is easy to install and use, it provides 650nm wavelength and adjustable focal length. This product is for locating, not for engraving. It's suitable for DIY lover, CNC engineer, artist and etc..    Features:  Red dot laser head with adjustable focal length. This product is for locating, not for engraving.  Made of premium quality material with great durability, long service life.  19cm long wire for flexible use. Wiring method: red is positive, black is negative.  Compact and lightweight, easy to assemble, convenient to use.  Designed for CNC laser engraver, suitable for DIY lover, CNC engineer, artist and more.    Note:  1. Please use heat dissipation equipment as much as possible for high-power lasers.  2. It's not suitable for continuous operation for a long time.  3. Size and color may be slightly different because of manual measurement and different light conditions. Thanks for understanding.    Specifications:  Color: Silver  Material: Metal  Wave Length: 650nm  Optical Power: 200-250mW  Voltage: DC 3-4.5V  Current: <350mA  Wiring Method: Red is positive, black is negative (XH2.54, the triangle mark is positive)  Laser Head Size: 12 * 44mm / 0.47 * 1.73in (Dia. * H)  Wire Length: 19cm / 7.48in  Item Weight: 18g / 0.62oz  Package Size: 16 * 6 * 5.5cm / 6.30 * 2.36 * 2.17in  Package Weight: 52g / 1.83oz    Package List:  1 * Red Dot Laser Head