0.3-4mm Universal 3mm Drill Chuck Connecting Rod Engraving ConversionAvailable in the grinding machine (dental drill) and other equipment.Quality assurance， you can buy at ease :)How to use : First governor speed adjustment in the "minimum or zero turn"， then turn on the power， adjust the speed， speed not more than 1w， to avoid damage to the shaft.Caution : Once installed on this universal chuck. Please do not direct adjusted to high-speed operation， or may cause the rear axle bend.Specification :Drill Chuck Dia : 0.3-4mmConnecting Rod Dia : 3mmPackage includes :1 x 3mm drill chuck1 x Connecting shaft