The Siemens SENTRON 3VA9133-0JF68 is a TA2.5 wire connector, part of the SENTRON accessories line. It's a circular conductor terminal designed to terminate six cables, supplied as a pack of three units. This is the terminal block you'd reach for when landing power or load conductors on a 3VA4 or 3VA5 125 A frame molded case circuit breaker. This connector also includes a terminal cover extended with holes for voltage testing — a nice touch for commissioning or troubleshooting without pulling the cover off. It's designed as an accessory for the 3VA4 and 3VA5 125 A frame breakers, so if you're building out a panel with those, this is the correct termination kit.
This connector mounts directly to the line and load terminals of 3VA4/5 125 A frame breakers. It's a screw-clamp type, so you'll need a torque screwdriver set to the values above. The pack of three covers a three-pole breaker. If you're wiring a panel with multiple breakers, order in multiples of three per breaker.