A heating device includes a flexible housing that defines a plurality of heater segments. Each heater segment includes a first compartment containing a first reactant, a second compartment containing a second reactant, and a frangible seal between the first compartment and the second compartment. The first reactant and the second reactant are configured to react exothermically upon contact with one another.

A self-warming bottle assembly includes a bottle that may contain a fluid. The bottle has a chamber that is fluidly discrete from an interior of the bottle. A warming media is positioned within the chamber. Thus, the warming media selectively warms the fluid in the bottle. A sleeve is removably positioned around the bottle and the sleeve may be manipulated. The sleeve inhibits the warming media from warming the fluid.

A heating device includes a flexible housing that defines a plurality of heater segments. Each heater segment includes a first compartment containing a first reactant, a second compartment containing a second reactant, and a frangible seal between the first compartment and the second compartment. The first reactant and the second reactant are configured to react exothermically upon contact with one another.