4.75" St. Louis Motor Demonstration Apparatus Subcategory_Color and Light supplied with keepers in a

supplied with keepers in a cardboard storage box for routine classroom work on field lines

providing lightweight projectiles for collision-and-ramp experiments where steel or glass would carry too much momentum or break on impact

supplied on a plastic-and-metal rack with a carrying handle for classroom transport

sized to give student bench setups a direct numeric reading without analog parallax

4.75" St. Louis Motor Demonstration Apparatus Subcategory_Color and Light supplied with keepers in aExposes every moving part of a two pole armature rotating between permanent magnets on an open 4 inch plastic base, running on 3 6V DC to illustrate both motor and generator operation.