I have 8 9 and 10 mm sockets that fit on a 6 mm hex keys. These came with a multitool. I don't know any one who sells these so I came up with a method to use ordinary sockets with hex keys. I found a 1/4 inch square bit of metal in the road that was likely a key for a shaft. It's only an inch long so I'm not going to cut it down. Useful sockets to carry are 8 9 10 12 and 14. Simply put 2 sockets back to back using the square shaft and drive them with a hex key. I carry an 8 mm hex key which will allow me to drive 9 10 12 and 14 mm sockets. So you may want to add a 6 mm socket to allow you to drive the 8 mm socket. I've broken 1 1/4 inch bolts using a 1/2 inch drive so expect you can break 14 mm bolts with a 1/4 inch drive. Not that you want to do this while riding. I have 14 mm socket built in to the crank puller so I don't carry an additional one. The 12 mm socket is used with the pedals which are seldom hard to get off so you can get away with using only the 1/4 inch drive.