From the Manufacturer

T-Handle Reamer is made of hardened and tempered tool steel with precision ground cutting edges. T-handle provides leverage for easier reaming. It has many uses including enlarging drilled holes. Capacity of 1/8" to 1/2".
ENLARGES HOLES: perfect for when a drill could cause cracking in materials
LUTHIER/GUITAR TOOL: enlarges bridge pin holes, headstocks, holes for tuners and volume/tone knobs
INCREASED LEVERAGE: T-handle provides leverage for easier reaming with greater control and easier turning
REMOVES BURRS: from wood, cut pipe, tubing and conduit. Inside deburring edge tool with capacity of 1/8" to 1/2"
ENLARGE & COUNTERSINK HOLES: In sheet metal, plastic and other materials with little effort
DURABLE: made of hardened and tempered steel with precision ground cutting edges