The AM-400 adjustable angle mounting bracket can be used for mounting Apogee downward facing sensors (such as our downward NDVI and PRI sensors) at different angles while mounted to a horizontal or vertical mast pole. This bracket can also be used to mount upward facing sensors (such as our silicon-cell pyranometers) in plane-of-array configurations. For applications that require absolutely level mounting, we recommend using one of our precision leveling bases, such as the AL-120.