The top of the bag is made of PEVA material, for keeping your food fresh, suitable for fruits, snacks,drinks, etc The bottom of the bag is made of aluminum foil, for keeping your food warm, different temperatures can maintain 4-8 hours of insulation Size of lunch bag: 24 x 20 x14.5cm, the top of bag:20 x 14 x13cm, the bottom of bag:20 x 15 x 9cm , The length of shoulder strap is adjustable(MIN:29cm, MAX:55cm) The bag is convenient to carry to school, work, picnic, camping,fishing trip etc. Several pockets on front and back for something needed,like phone,tableware, transportatio..