Thanks buddy! I had a feeling 1/8” was about right.I'm pretty certain the hole I drilled in mine was 1/8 inch, and I just did it freehand with a hand held drill, but I've found out since then that the taps can be very brittle and that wasn't a great idea, but seemed to be fine! I took my WannaWanga D ring to an antique store that had old military stuff and found a harness or something that had a d ring the right size