All right, great. It is less designed than transformed. Someone took a 3/4 inch by 16 foot tape measure and converted it to metric by adding some length and printing the tape in millimeters. The really annoying thing is the "+3" cast into the case for internal measurements. it is *NOT* fully metric. Those 3 inches are 76.2mm. Don't forget this number and don't forget to add it to your internal measurements. Why didn't they make it to 75 or 100? The specifications state that the width is 19mm. , or about exactly 3/4 inch. I used it to measure the width and got a width of 18mm. Why not 20 or 25? approx 180. Mine often snags and doesn't retract smoothly - probably just needs some silicone spray. The hook seems to be well made and precise free for inside and outside measurements.