Joytech 3.93'' (100mm) Diameter Spinning Top Base K9 Crystal Glass Concave Mirror, Great High End Transparent Surface Double Concave Top Accessory DZ04

It is exactly as described. Nothing wrong, nothing wowing, you get exactly what you pay for.

Works very well with my foreverspin official tops. Draws the top in toward the center where it can perform it's mesmerizing dance

This is a great size and has a nice gentle concave for stabilizing most spinners. The raised edges help keep errant spins from flying off the surface and can help a bad spin become a decent one. The glass is clear and clean. The only reason I don't give it 5 stars is there are visible chips and nicks on the extreme edges of the glass. This doesn't affect the spin but for those who are bothered by imperfections, they are noticeable. Even with the slight flaws, I would highly recommend this base!

Shipped fast. 5.5 minutes spinning!

I read the reviews and I came to the conclusion since some people complained about very minor inconsistencies with the grinding of the edge of the glass so I simply purchased the one with the black frame around the glass. The black edge protects the edge of the glass and in addition it helps create a boundary so that the top is more likely to stay on the glass when you have less than the perfect start up spin. I’m definitely happy with my purchase and this is probably the most reasonably priced concave glass lens that I’ve been able to find.. End it comes beautifully packaged in bubble wrap inside of a nice presentation box.

I got my first top in 30 years today to have something to fidget with. And i bought this base. The top and the base are made by the same people. I have to say i got just under three minutes on my first spin but this thing is loud! Im glad im by myself most of the time. It has a loud humming sound while the top spins. The base also seems so fragile. But it works.

I really love this lens and have ordered another one! It is definitely concave on both sides. The glass is very smooth on the top and bottom. More experienced folks with spinning tops have said to use the oils on your hands or face to lubricate the glass. But I do not find the need. You be the judge, however. If you feel the top/bottom of the glass, it's smooth to the very edge. Right on the edge it goes down at an angle and then goes flat on the sides. That part of the lens, and on the sides, are not smooth like the glass on the top and bottom but is safe to handle. With regards to the bottoms of tops, I don't feel there is any danger of scratching the bottoms of the tops because of the way it is designed. Highly recommend!

I actually like this. I can spin my gyro and, unless I stupidly spin it quite wildly, it will stay on this platform and center itself even on unlevel surfaces.

This is exactly what it says a 100mm diameter concave on both sides glass disk just what i wanted for spinning a gyroscope and messing with light rays but the one i was sent has some chips in the edge not bad enough to ruin the function of the disk but still enough to show poor quality control

Worked well for a while, then broke when it fell from the desk onto carpet floor. Surprised given it was ~75cm drop and nothing protruding onto the glass. Oh well, wasn't expensive, it happens.

It works acceptably as a spinning top base, but the finishing on the edges of the glass is disappointing. In the pictures it looks smooth and minimalist, but in reality the edges are quite rough with some chipping and discolouration - nowhere near as elegant as advertised. Would suggest buying a vast from a more well-known brand instead…

Muy bueno el cristal y va Perfecto!