Package contains Digital Inclinometer and a Companion Unit. Also comes with instructional manual, illustration booklet and connecting cable. Two-inclinometer techniques and procedures are well defined in the 5th edition of the AMA Guides. It is emphasized that spinal motion is compound, thus it is essential to measure both angles. Acumar Dual Inclinometer can simultaneously capture both angles by the press of a single button. It allows up to six pairs of data for viewing and recording to greatly speed up data capture and analysis.