A question for integrating sphere owners

I’ve been playing with a 16” integrating sphere hooked to the prototype of my LED analyzer (Any interest in a LED/Battery analyzer device?).

I’m trying to get a feel for how other people’s spheres behave. What is the size of you sphere (preferably inside diameter) and your lux to lumen conversion factor?

My integrating sphere is 6.7 inch inside, made of metal (aluminum).
Conversion factor is trimmed to 0.01 by using a grey filter (layer of Scotch ‘magic tape’) in front of the sensor chip with its IR filter. I’m using the sensor without the opaque dome from the stock sensor head.
With that factor the readout is directly in lumens when the meter is in x100 position.

Where did you get a metal ball?

The project is described here.