These backpacks are very traditional. they have no metal parts, only thread! They measure about 36 cm (14 in) high and about 25 com (10 in) wide. The thread is acrylic, so the bags last a long time, and can be machine washed in cold water, and then air dried. The Wayuu women start learning about knitting when they are little girls watching their mothers knit. They gain more extensive training during puberty, when they are cloistered for long periods of time and their moms and grandmothers (the only people who can see them during this period) teach them sewing, weaving, cooking, and other useful skills. Wayuu women are such skilled knitters that they even knit while they walk around!