I have read some antiquated and interesting posts:) I am attaching a 50 amp Seimens disconnect panel for a new hot tub install. My question is do I use a 60 amp double pole breaker OR a 40 amp double pole breaker at my Main house Panel (also a Siemens)? They do not make a 50 amp... My thinking is to go with the 40 amp as you want to preserve the circuit. The manufacturer recommends a 50 amp breaker on the disconnect.
Thanks!

A 50 amp breaker is a standard size breaker (see NEC 240.6).

So either the store you are working with is remiss or they have failed to check a crossover list to see what 50 amp breaker will fit your box.

You might want to search the Siemens website as an additional resource.

Home Depot has none, in Canada. T0 clarify, the disconnect panel comes with a 50 amp GFIC breaker, I'm asking about the main panel that will service this exterior disconnect.
Thanks!

The connection requirements to the main panel should also be covered in the equipment installation instructions which you need to carefully follow...
The circuit breaker for the main panel needs to be at least 50 ampere, 2-pole... which I expect is recommended by the manufacturer...

**Using a 40 ampere, 2-pole at the main panel may not be large enough for the load of the tub and will violate your warranty. Order the correct breaker, do it right.