These filters compare the price of the last print to the pre-market high and the pre-market low for the current trading day.  This is expressed as a percentage.  100 means the last print was at the pre-market high for the day, 0 means the last print was the pre-market low.  50 means that the last print was half way between the pre-market high and the premarket low.

This filter is available before the market is open, while the market is open and during the post market session.

It is possible for the value to be above 100% or below 0% if the price continues to go up or down after the pre-market session. The best way to see stocks trading above their pre-market highs is to set the minimum filter to 100 and leave the maximum filter blank.