Mercury switches were once common in bimetal thermostats. Low-precision thermostats use a bimetal strip and a switch contact. Blades for bandsaws and reciprocating saws are often made with bimetal construction. A bimetal could be regarded as a thermally activated bimorph. It also includes some rare cases of bimetal collector coins (titanium, niobium, etc.). A bimetal bar is usually made of brass and iron. This interrupts the circuit and can be reset when the bimetal strip has cooled down. A bimetal switch or wax motor opens the detergent door during the wash cycle. They have minted more bimetal collectors' coins than gold coins. This type of ammunition is labeled "bimetal". In some applications the bimetal strip is used in the flat form. After a short time, the bimetal will cool and reconnect. Bimetal strips are used in miniature circuit breakers to protect circuits from excess current. Bimetal blades with high speed steel teeth, including cobalt grades, are now the norm. Bimetal strips are also used in time-delay relays, lamp flashers, and fluorescent lamp starters.