The 3RT2926-4PA01 is a combination screw set from Siemens SIRIUS, supplied as a bag of 100 M4 screws for the main-circuit terminals on 3RT2.2..-4 contactors. This is the hardware you need for terminating power cables on S0- and S00-frame contactors in that series — not the contactor itself, but the fasteners that keep the connection torque-consistent across a panel build.
Designed for the main circuit of 3RT2.2..-4 contactors — the -4 suffix indicates the contactor variant with screw-type main terminals. The M4 thread matches the terminal clamp on those contactors. If you're replacing a lost screw or building a batch of panels, this bag gives you 100 pieces, enough for about 33 contactors (three main terminals each).