The tabs do as expected. What's not expected is visual, or more accurate lack of visual. The font is around 6. This combined with dark colors [red - purple] make it impossible to READ the book tabs. The only colors which are truly viewable are yellow, orange, and white. Being over 40, I had to return them. There are other "rainbow" ones available in pastel colors which work fine, these are not them.
FALLS SLIGHTLY SHORT OF EXCELLENCE BECAUSE THE PLACEMENT RULING PROVIDED CAUSES THE TABS TO BE TOO CLOSE, IF NOT OVERLAP, EACH OTHER. THERE NEEDS TO BE AT LEAST A 6mm SEPARATION SPACE BETWEEN THE PLACED TABS TO MAKE IT EASIER TO HOLD AND LIFT.