Spinning Base - 150mm Glass Concave Lens

150mm (approx 6") Double Concave Fused Silica Glass Optical Lens - Thickness 0.45” (11.5mm) Precision Machined Double concave lens. Fused silica. Harder and more durable than most for years of spin enthusiast fun Functional, Elegant Frosted reducing glass lens edges. Polished to a conversation-starting shine for record-breaking spins Suits All Spin Tops Made to extend the spin-duration of any spinning top’s contact point. Use one of your own, or take on from our collection for a spin Hobbyist’s Delight Know a spin top hobbyist? Our spin base promises to make a special someone smile and spin for years Features: Diameter - 150mm/15cm (5.9 in)Thickness - 11.5mm +- .25mm (0.45 in +-.01 in) Weight - 531 g (15.2 ounces)Radius of Curvature - 1500mm - center of lens is 3.3mm thinner than the edgesMaterial - Fused Silica glass*Holds up better than standard plate glass or a standard spinning mirror but handle with care as it can still shatter if dropped from a height Recommended for ages 16+GIF