The size of underwear is marked with numbers+letters, and the number is the size of the lower bust. There are two sizes of centimeter and inch, which are corresponding. The lower bust size is converted into 70cm = 32；; 75cm = 3480cm = 3685cm = 3890cm = 4095cm = 42。 The letters on underwear refer to the size of the cup, which is the difference between the upper body and the lower body. The size of the cup represents the size of the breast. The difference between each cup is 2.5 cm, and the smallest is AA cup 7.5 cm, A cup 10 cm, B cup 12.5 cm, C cup 15 cm and D cup 17.5 cm. A cup, upper and lower bust difference10 cm; The cup is B, and the difference between upper and lower bust is12.5 cm; . The cup is C, and the difference between the upper and lower bust sizes is 15 cm. Bra (Brassiere, abbreviated as BRA), also known as bra, bust, bra and corset, is a kind of clothing used by women to support and beautify their breasts. There are many kinds of bras, which are divided into full-cup bras and? According to the material classification, cup bra and half cup bra can be divided into ordinary type, beautiful type, soft type, sports type, auxiliary type and health care type.