Each wheel is 45 lb, the axle is 44 lb. If I put the collars that came with the bar, it would be 135 lb.
For reference, the axle is another steal on Amazon for $159 and free shipping.
I didn't get any advice on using them. I'm not too worried about cracking. The weld beads look like they were laid by a professional, so if they don't hold, nothing will.
This is what I use. It's a true 20kg, 2" axle. And it's cheaper than IM's. Not to take anything from IM. They're one of the best companies on the planet to do business with, but I like that the one below is 44 lb vs IM's 33 lb bar. It makes mathing weight easier.