Back when I purchased it, the Tavor was shipped with a M21 reflex sight from Meprolight.
Here is the full sight picture.
Being a reflex sight, the brigthness of the recitule depends on ambiant light. I have found it very efficient under most lighting conditions. In full sunlight, the blue tint is perfect.
At night, a tritium light source illuminates the reticule. It works fine but I am unable to test it as shooting at night is not legal in Canada...
The M21 works well with one exception. If the target is in bright sunlight and the M21 is in the shade, there is not enough ambiant light for the reticule to shine. Since there is no brightness control, it is impossible to see the aim point.
That limitation caused the Meprolight to have a very negative reputation when Tavors where initially shipped.
A solution does exist. It is the Wash Out Remover. I have not tested this product as it did not exist when I had my M21. Hopefuly it is as good as they claim it to be.
The M21 is a very efficient mirror, so be careful if your life depends on it.