Spring Tool Balancer Retractor (1.3-3.3 pounds), (Sumake SA-2203)

Amazon description says 1.3 pounds minimum, but the label on the tool in the picture says 3.5 kilograms min (= 7.7 pounds)... which is it?

Is the tension constant throughout the length of travel?

Does this tool have cable lock, so the length can locked to a adjustable hang length, and then released by pulling slightly to release the lock?