Alkaline
Alkaline PP3 9V Batteries are commonly used in smoke alarms and as a power source for small electronic devices such as electric guitar pedals, microphones, test equipment and remote control equipment.

Lithium
Primary Lithium PP3 9V batteries are often used in smoke alarms or applications which require longer running times that Alkaline batteries can give.

NiMh
NiMh (Nickel Metal-Hydride) PP3 batteries are used in 9V applications which are used reqularly such as stage microphones or remote control equipment. It is not recommended to use rechargeable PP3 batteries in saftey critical stand-by applications such as smoke alarms due to high self discharge.