These steel hanger bolts have a wood screw on one end and machine threads on the other; overall lengths are indicated. They require a pre-drill between 7/32" and 15/64", depending on the material.
For flush mounting or joining material, use the steel insert hanger bolts. These are 1 1/2" overall with a 3/4" long external screw thread and 1/2" deep internal machine thread; they require a pilot hole from 17/64" to 9/32" in diameter.
All are sold in bags of 10.