Connecticut Electric manufactures new high quality replacement circuit breakers for Zinsco load centers that accept Zinsco QC style circuit breakers. Circuit breakers should only be replaced with new tested and Safety Agency Listed circuit breakers, never used or refurbished ones.
From the Manufacturer
This 120/240 volt Zinsco 50 amp, double pole, thick series replacement circuit breaker is used in a Zinsco load center. Typical applications, up to 22,000 watts, include electric ranges (15 KW - 21 KW), electric ovens and central residential air conditioners (240 Volt, up to 23,000 BTU). These are only suggested applications and cannot assure compliance with all local codes. Please check local electrical codes before starting any electrical project.