If you are referring to the circuit breaker that is in the photo below yes it is the 120Amp Circuit Breaker and yes you can get it from Terminal Supply Company. I will try to find a part number for you.
[edit] well it appears the part nmber on it there is CB185120, i will check to see if that is the same as it is for TSC. [/edit]
[edit 2] You can get it from Terminal Supply Company via part number CB3-SM-120. They are on page 88 of their pdf catalog but there is no price listed. The website though is
www.terminalsupplyco.com i hope this helps. [/edit 2]