SATCO Lighting 67-134 Remote Emergency Light, Low-Voltage Backup, Single Head

That depends entirely on the spare remote capacity of the host unit, which is rated in watts at a given low voltage. The 67-134 is a low-voltage remote head, so before adding it, check the remote capacity and output voltage on the emergency unit or inverter you plan to feed it from. Match the voltage first, then confirm the unit has the wattage headroom left after the heads already connected.

Use a remote head when you have one emergency unit or a central inverter and need to throw light into a stairwell, a back corridor, or a room that has no room for a battery box. Use a self-contained unit when the space is standalone and you don't already have an emergency source to wire back to. The 67-134 is the remote type, single head, so it is a companion to an existing low-voltage backup source rather than a replacement for one.

6.00 inches by 4.25 inches, listed as W 6.00 inch and H 4.25 inch. That is a compact head, small enough to sit above a door or on a corridor wall without dominating the wall plane, and worth checking against the junction box or backplate you are mounting to.

One head. If the space needs light thrown in two directions from a single mounting point, a double-head remote is the right call instead. For a single egress path or a one-direction throw, the 67-134 covers it.