I think I would have just purchased a 100 amp 24 space main breaker value pack For $52.
Also comes with 4 "free" breakers.
Buying stuff al le cart just cost more in time and money.
Yes however the other box is already installed and I'm unable to take it back as it is past the 90 days. So it was either buy a new box for $50 and try and sell the one I have now or spend $50 on the main breaker kit.