The patented Rotary Thread Inspection Tool accurately inspects internal screw threads for functional size and depth faster and easier than conventional methods. The unique Rotary Thread Inspection Tool safely checks internal threads while eliminating operator arm and hand fatigue and repetitive motion injuries. The instrument features a portable and ergonomic design engineered for industrial applications. The unit is supplied with high performance rechargeable NIMH “quick change” batteries that provide long lasting hours of operation. It also includes a patented depth control feature with automatic reversal.