Full size breakers vs tandem breakers?

Not enough space for circuit breakers - two breakers in one slot So if the manufacturer has designed a panel to take only full height breakers, then you can't use the pancake breakers or the twins two slot toaster Flip both of them upside down and compare the slots on them where they slap into the busbar I bet the slot is much larger on the regular

two slot one slot chording From bar one the conductor goes to the top of slot one , than to bottom of slot four and then to bar two breakers similar to those