"I have an old drill and could not find the right key. It was not listed any where. I found the chuck was 1.5 mm to 13 mm which was stamped on the chuck. At the low price of this key I took a gamble that 13 mm was the size of the key. It said universal 1/2 key. which is 13 mm. The key fits fine and works without any problem."
"The chuck key for my Fermin drill went walk about recently and I needed a replacement PDQ as I was in the middle of some work. Checking local "sheds" the prices were very high. I checked at Screwfix and the prices were more than reasonable, but one reviewer suggested that the product was inferior. However, I took a chance and bought two of them. I would agree that they are not the best quality, but they work well and are more than adequate for the job. Only time will tell if they will last, but for intermittent use they are excellent."