and in most cases, the cigars rolled, of approximately 65–70% and a temperature of . Dry cigars become fragile and burn faster while damp cigars burn unevenly and take on a heavy acidic flavor. Humidors are used to maintain an even humidity level. Without one, cigars will lose moisture and acquire the ambient humidity within 2 to 3 days. A humidor's interior lining is typically constructed with three types of wood: Spanish cedar, American (or Canadian) red cedar, and Honduran mahogany. Other materials used for making or lining a humidor are acrylic, tin (mainly seen in older early humidors) and copper, used widely in the 1920s–1950s. Most humidors come with a plastic or metal case with a sponge that works as the humidifier, although most recent versions are of polymer acryl. The latter are filled only with distilled water; the former may use a solution of propylene glycol and distilled water. Humidifiers, and the cigars within them, may become contaminated with bacteria if they are kept too moist. New technologies employing plastic beads or gels which stabilize humidity are becoming widely available. A new humidor requires seasoning, after which a constant humidity must be maintained. The thicker the cedar lining the better. Many humidors contain an analog or digital hygrometer to aid in maintaining a desired humidity level. There are three types of analog: metal spring, natural hair, and synthetic hair. In recent times Electric Humidors, which feature a thermoelectric humidification system have become popular for larger cigar collections. Accessories A wide variety of cigar accessories are available, in varying qualities. Travel case Travel cases protect cigars from direct exposure to the elements and minimize potential damage. Most come in expandable or sturdy leather, although metal leather and plastic lined cases are found. Some feature cardboard or metal tubes for additional protection. Tube Cigar Tubes are used to carry small numbers of cigars, typically one or five, referred to by their number of "fingers". They are usually made from stainless steel, and used for short durations. For longer, a built in humidifier and hygrometer is used. Ashtray Ashtrays are used for collecting the ash produced by the cigar. Such ashtrays are typically larger than those used for cigarette smoking. Holder A cigar holder is small tube in which the end of the cigar is held while smoked, to protect the hand from acquiring the odor of a burning cigar, historically