This is a single palo santo stick. It measures on average 4" but they are hand cut so they do vary in size.
To cleanse with palo santo begin by lighting the end for 30 seconds to 1 minute. Blow out the flame and allow the stick to burn as incense or go room to room. It also can be kept in a ceramic dish with a charcoal disc to burn the entire thing.
One stick should last you more than one cleanse depending on how big your space is or if you want to burn it all at once.