18650 flat top unprotected batteries are a type of rechargeable lithium-ion battery that have a flat positive terminal without a protruding button. They are commonly used in devices that require a continuous high discharge rate. Unlike button top batteries, flat top batteries have a more compact design, which allows for a tighter fit in some devices.

However, it is important to note that flat top batteries may not be compatible with all devices and may require additional equipment, such as a battery holder or spacer, to be used effectively. Additionally, as unprotected batteries, they do not have built-in protection circuitry, which means they should be handled with care and only used in devices with proper safety mechanisms in place. Overall, 18650 flat top unprotected batteries are a versatile and powerful option for those looking for a high-performance rechargeable battery.