Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Thermos for bike commute or backpacking

Best Thermos. Keeps coffee nice and hot, even when used while commuting on bike. Has been spill proof for me on my commute as well. Great product, and recommend for anyone looking for a good outdoor quality Thermos. Recommend getting a bottle brush for cleaning due to narrow opening. The Thermos may not fit in all cup holders but I know it does fit in Mercedes GL and First Generation Xterra cupholders.