3/8" locking extensions

I was changing spark plugs today and I couldn’t find any medium length extensions. There’s a couple short ones then the length jumps to 6-8". Since in the 3-5" range would have been handy for me, can we get some? Also, I’d like to request the SIG group look into something like this Craftsman locking extensions. The sparkplug socket kept getting stuck on in the plug when the extension would easily separate from the socket. With a locking extension this wouldn’t happen.