I'm sold on this product!!! Used it for my last 5 batches and have been able to keep temps anywhere from 55-70 depending on the amount of 2 liter bottles I use. This is at an ambient room temp of 78-82! If you can't afford refrig or other coolers - this is the product for you
I live in S California and its difficult to keep low temps without a ref rig - You might look into Cool Brew - I was skeptical at first but by using only 2-4 frozen 2 liter bottles I can keep the temps in my carboys from 55-65 degrees