Set of 2, King, Pottery Barn SleepSmart 37.5 Technology Temperature Regulating Waterproof Pillow Protectors, NWTs, Retail $80 36" l x 20" w As you sleep, temperature and humidity build-up and become trapped in your sleep environment. Sleepsmart 37.5 technology uses naturally derived fibers that work continuously to trap heat when cold or evaporate excess humidity when warm, before sweat can form. Body heat-activated performance offers comfort personalized to each sleeper's need for warmth, so you stay asleep longer. 60% polyester/40% 37.5 performance polyester double knit construction. Zipped closure and white satin piping. 37.5° activated carbon particles absorb odor molecules to keep bedding smelling fresh. Diamond pattern sleep surface reverses to a breathable waterproof lamination, backed by a polyurethane nonwoven material for added protection against fluids to keep your pillows clean and dry. The waterproof lining is whisper-quiet and soft for an extra level of comfort.