FAQ: How do I know the concentration of my index primers? 

For index primers provided in tubes, the last four digits of the lot number is the release year and month of the kit lot. Any kit released in or after Dec 2014 (lot number ending in 1412) is 10 µM and any kit released before Dec 2014 is 25 µM. In addition, the concentrations are now also printed on the tube labels. Any index primers provided in plates are 10 µM.