If I remember correctly, they are 1/4" threads. But I'm not too sure. You should contact Totem directly via their website "www.totemacoustic.com". I have a pair of Sttaf's and I actually removed the plinths (the same ones are on the Arro's I think) from mine and replaced them with a set of the Totem Claws. It made a huge difference in the overall sound of my Sttaf's. You might consider doing the same with your Arro's too. Good luck
