The Siemens 3RT1946-6A is a replacement contact-piece kit for a SIRIUS S3-frame power contactor. It covers the main contacts only — 3 NO poles — and ships as three movable and six fixed contacts plus the mounting hardware. The kit is rated for AC-3 duty at 45 kW, which means it handles the inrush and breaking of squirrel-cage motors up to that load. If you are rebuilding an S3 contactor in a panel, this is the factory-matched set of silver-alloy tips and arc runners, not a generic substitute.
The 3RT1946-6A is marked as a phased-out product. The official successor is the SIRIUS 3RT2 contactor series — meaning if you are stocking spares for a legacy S3-based panel, this kit is the correct consumable for the installed base, but new designs should move to the 3RT2. No last-time-buy date is recorded, so treat it as a critical-spare item — one in the cabinet before it fails.