The cap is the base of the wig onto which hair is attached. Wigs are available with several different types of caps and the hair of the wig is then attached to the cap using various techniques. Each cap type has its own distinct advantages. On most wigs, hair is attached in "wefts." These are strings of hair doubled over and sewn closely together in long strands. This string is then machine sewn, hand sewn or hand tied horizontally onto the vertical lines of a wig cap. A standard cap is the most common and most affordable cap design. The layers of hair are machine-sewed onto the cap, which has a closed lace layer at the crown. The hair is pre-designed into a specific style and the crown is often lightly teased or crimped so you cannot see down through to the cap. This type of cap often gives the hair a natural lift at the crown for volume. A capless wig is very similar to the standard cap design. However, instead of the closed lace layer at the crown, it has vertical lace strips with open spaces between the wefts. The open-wefting in the crown, back, and sides allows for maximum ventilation. This makes the cap lighter weight and cooler than a standard cap. Monofilament caps are constructed using a thin, breathable nylon or polyester mesh material at the crown that gives the illusion of skin and assumes the wearer's natural scalp color by partially revealing the scalp below. Monofilament caps offer the most natural look as well as styling versatility because each hair is individually hand tied at the crown so the hair can be parted and brushed in any direction. The entire wig may be hand tied, or the wig may have a monofilament crown with wefted sides and back. Monofilament wigs are an especially good choice for those with severe or total hair loss as the cap is soft, unlike cloth material, which can be itchy to those with sensitive scalps.