“U.S. No. 2” consists of pears of one variety which are mature, but not overripe, carefully hand-picked, clean, not seriously misshapen, free from decay, internal breakdown, scald, freezing injury, worm holes, black end, and from damage caused by hard end, or broken skins. The pears shall also be free from serious damage caused by bruises, russeting, limbrubs, hail, scars, cork spot, drought spot, sunburn, sprayburn, stings or other insect injury, disease, or mechanical or other means. (See §§ 51.1306 and 51.1309.)