I have an EX21. Mine is an older version so my tensioner is up front by the blade. The newer ones have a tension knob at the back. The last time I was at Seyco in Rockwall Texas, I messed around with the newer model with the tensioner in the back. It is a no brainer. There are quick release knobs for the blades, a quick twist of the knob and you are ready to saw. I highly recommend the Ecalibur line of saws. They have a lifetime warranty and I have found nothing but GREAT service from the distributors. Practically zero vibration. You can change and tension a new blade in seconds.