These are the same style hand grip strengthener that several others are selling here. The type works well. However, the biggest reason I picked these is I got two for the price many are selling one.
I still like this and still use it, just more gently on my legs cuz apparently they're weak. I love this. I have scoliosis, so my back hurts quite a bit. Being single and living alone, it's not easy to find someone who wants to massage my back without having to pay for it. haha. I love being able to just run this across my back a few times and feel the muscles loosen up. As a side note, when I use it on my thighs, I get some pretty decent bruising. That's the only part of my body that gets bruised from it, so it's most likely just sensitive skin.
We tried one out at a big box store, and she just had to have it. It saves me cramps in my hands, and relaxes her, so it's a win in my book. My wife loves this thing.
The bag is very durable! !. I'm obsessed with this backpack. I was nervous to buy this because other reviews mentioned it didn't fit a large water bottle but it does. The carry a 32oz Nalgene narrow and wide mouth and it fits perfectly.
Now its better. Comfy, have nice bounce. I added my own inserts since my for some reason my foot was slipping to the front.