So I got the medium size and was surprised that it would be heavier because your thinking heating pad, but it’s super light. I tested at home on a cold day and it kept that area warm. I can see when I get to use it in the hammock it will feel great. I so can’t wait to test the battery length for. Now the cons. Being a new product I can see the price to be high, but I was a little Hesitant to buying it. But we will see if I got my monies worth on next cold hammock hang. I would have like to have been able to get the larger battery pack, but I hope down the road I will. The last thing I was sure if you are taking this on a back packing trip can you pack it with out damaging the heating elements? Will have to see later on how Rugged it will be.