The fabric is a Giza 45 denim, 100% cotton. Denim is a cotton twill in which only the warp threads are dyed while the weft stays pale: hence the diagonal visible on the face, the lighter reverse, and the way the garment lightens at the points of greatest wear. Pure cotton gives breathability and strength, and with washing the hand softens while the cloth keeps its body. The Giza 45 designation is the one specified by the fabric maker.