I've been very happy with the purchase. This is a link to the better quality of the vests and the one I'm keeping. 3 zones: lower back, upper back and neck, front. I usually keep it on low or medium, but do suggest getting a bigger battery as the 10,000mah battery is only good for a few hours and best. Pocket for battery is poor design choice being front right pocket but that is a small price to pay for staying warm working outside in the snow on people's broken hot tubs.

https://smile.amazon.com/dp/B09CT1V128?ref=ppx_yo2ov_dt_b_product_details&th=1&psc=1