First off these are rare and very hard to find in this condition. The sale is for one pair ..They are sold for parts or not working they are not tested I do not know if they work properly. You might need to work on them to get them to work 100%. Sold as is. With that said one looks immaculate like nothing has ever happened to it and the other one is a little bit dark inside of the bulb area and it does look like it might have been tested or slightly used and it looks like it might have burnt out. The one that might have been burnt out when you move it it does sound like there is dirt or some rust or something on the inside I am not going to take this apart or do anything with it I will leave that up to you.

These measure about 8 in in diameter. And about 6 to 6 in in depth