Originally Posted by Bengt
For the same reason baseball players train with more than 36 oz. I had to twist the green one at least 50 times a set to feel it working. It got tedious. I think the blue one would have worked better for me from the start. I had a mild/med case of TE - pain on serve and ohbh. Btw, I "recommended"; not "insisted" fwiw. Buy all 3. They're cheap.
This isn't baseball. 10lbs, 15lbs, 25lbs....why 25lbs? Unless you have a locked arm and swing from the elbow or arm every ball, its difficult to understand why you need to 'train' with a twisting force that is x35 more (25lbs) than the racquet. The purpose of the Flexbar is to strengthen and re-align the direction of the fibres in the tendon, not strength training for caber tossing. A huge part of prevention is technique related and staying loose. Correct that and its difficult to see why you would need a 25lbs twisting force over 10lbs or 15lbs.