Oooo i was intrigued with the answer to this. It must be 45mm ish surely
People used to fill them with sand and bash them down before weighing them in. So I've heard. Never actually held any in my hand in my lifetime and I'm 40-ish. Seen it in a dug hole but no way to tell from that it was...
Scroll to the bottom of the forum. On the left there's a tiny paintbrush. Click that and change your style, a couple of them should work and one probably not.
I am aware of the issue and am working through it.