These drill chucks look to be first quality. I have purchased a "few" now and have received many that have the center hold and chuck split (the "X" on the face) off center and this makes the chuck totally unusable. These chucks are drilled and cut spot on....the only problem is the O.D. of the chuck. All four in this set measure 4.18mm to 4.20mm. I need a nominal 5.00mm chuck base diameter to fit the Utopia Rotary Tool I purchased. The supplied chucks are the same under-sized chuck and leave me with a BIG problem centering my tools in the chuck!