These bikes look and feel like normal mountain bikes, until the officer-rider flips a switch. A small electric motor system engages to augment the power of the rider, much like a turbo boost, so the rider can easily pedal speeds up to 20 mph, while saving their strength for the crime scene. An officer user of the bike comments, "Electric bikes give us the speed to respond to emergencies, reduce the risk to the public as we're getting there, and still leave us in a physical condition to be able to deal with a situation." The bikes are equipped with rechargeable batteries that are easily exchanged for around-the-clock use. The extra battery capacity allows for the use of lights and sirens, which give electric bikes the ability to stop traffic. Used batteries can be recharged back at the station with an automatic 110-volt battery charger. A full charge costs approximately 3 cents and can power the bicycle up to 15 miles before recharging. An optional battery meter tells officers how much "juice" they have. Regenerative circuitry enables the ZAP to recharge its battery while coasting downhill. The ZAP motors are virtually silent. Although ZAP bikes may cost a little more than conventional bikes, many departments believe the improved job performance is worth it. In some communities, air pollution grants can fund the incremental costs in adding them into patrol fleets.