The 250-203. is a 3-pole grey PCB Terminal Strip with push buttons and front-entry wiring. This terminal strip has tin-plated contacts and a polyamide 6.6 insulator. It accepts 24 to 16AWG wire size.
Cage Clamp? connection method
Simple, push-in terminations of solid and ferruled conductors
Termination/removal of fine-stranded conductors via push-buttons