This has helped me immensely in my rehab. It's incredibly important after Tommy John to stay on schedule and get your throws in. Not only do you need to get everything "back" but your mechanics are likely to be pretty screwy. This will help.
My fiance is pretty thankful for this. Her hand hurt pretty bad after the last session. I felt awful for her because she was trying to be supportive and wonderful. I'm lucky to have her. I'm also lucky to have great teammates who are really supportive of my recovery and are always willing to help out.
Even in 38 degree weather....under covered cages...in the Northwest.