Features Physics Demonstration: The primary and secondary coils are mainly used for middle school physics demonstrations of electromagnetic induction and verification of Lenz's law, and are very practical accessories. Sensitive Enough: The electromagnetic induction coil is sensitive enough, and it is an indispensable experimental instrument and teaching instrument. Mainly Composed of 3 Parts: The physical electromagnetic induction helix is composed of a primary coil, a secondary coil and a soft iron core. Easy to Operate: The physical electromagnetic induction coil kit has a stable structure, easy to use, and has a light and delicate shape, which is easy to operate. Sturdy and Durable: The solenoid coil is made of selected metal materials, which is durable and scratch-resistant, which can satisfy our use. Specification: Item Type: Primary Secondary Coil Set Material: Metal Model: 24010 Primary Coil: 200 Turns Inner Diameter: Approx. 11mm / 0.43in Outer Diameter: Approx. 15mm / 0.59in Secondary Coil: 370 Turns Inner Diameter: Approx. 24mm / 0.94in Outer Diameter: Approx. 30mm / 1.18in Package List: 1 x Primary Coil 1 x Secondary Coil 1 x Iron Core Stick Package List 1 x Primary Coil 1 x Secondary Coil 1 x Iron Core Stick