Stirling Engine Accessories Metal Flywheel for Lab Experiment Replacement Supplies High temperature resistance flywheel Great accessories for Stirling Engine model Material: Metal Color: As pictures shown L Diameter: Approx 50mm/ 1.96inch Inner Hole: Approx 3mm/ 0.11inch L Diameter: Approx 25mm/ 0.98inch Inner Hole: Approx 3mm/ 0.11inch