Question for Keystone Tablet Plus owners - How big is the lock hole?

I know about the lopp website and the review of the Keystone Tablet Plus, but for my needs it will work fine.

My question is if anyone knows how big is the hole on the Keystone Tablet Plus? I have one on the way and wanted to buy a lock for it.

Also, if anyone does plan on buying one of these things despite the review, periodically look on Ebay. I bought a brand new one in the box for twenty five bucks, they are normally seventy.

Thanks!