This manual is for the USGS multifunction bedrock-aquifer transportable testing tool (BAT 3). BAT 3 can be used to obtain a series of hydrogeologic characteristics of fractured-rock aquifers, including aquifer permeability, fracture density, hydraulic conductivity, porosity, and fracture water chemistry. This manual introduces the basic structure and function of BAT 3 and provides basic operating steps for using BAT 3 to obtain hydrogeologic characteristics.