Some battery testers may have a long-reach extended sensor. This is a lead which plugs into the device and has a flatter sensor at the end. This not only allows for extra reach but also means the sensor can be placed in tighter gaps, like underneath fridges or washing machines. It also keeps the circuitry inside the main box of the alarm further away from potential water damage.
Nail hook
On some battery testers there may be a nail hook: this makes the device capable of being hung on a vertical surface.
