because there comes an allen key with every Ovation.
But if you happen to have lost yours, you will quickly learn, that the only thing that is "standard" with the Ovation allen key is the 3/16" size, because the allen keys that you can buy from your local hardware store won't help.
Either the long arm isn't long enough or the short arm is too short. Or both ... or the other way around.
Same thing happened to me. I misplaced my allen key that came with my Ovation anf hard to address a slightly too bent neck. I did buy two other allen keys - one in a 8-piece set, the other as a single key - only to find that either the long arm was too short or the short arm was even shorter. Regardless, I could not find the means to properly adjust the neck without wrecking the allen socket, the allen key or - once again - both.
Thomann delivered quick and the allen key that arrived was of a good fitting quality and with a long arm long enough to reach wholly into the allen socket and with the short arm long enough to allow for a precise, safe and convenient adjustment of the neck bow.
Oh, and yes, the original Ovation allen key reappeared a day after the Thoman replacement arrived. Bugger!