3/8" drive speed wrench
The object in the image is a vintage S-K 3/8 drive speed wrench, model number 45181. Additional details: It is approximately 16.5 long. It features a knurled handle for better grip and faster turning of fasteners. The S-K marking indicates it was manufactured by S-K Hand Tools, a tool company known for quality tools. This type of wrench is also known as a speeder wrench. It is designed for quickly tightening or loosening nuts and bolts in applications where high torque is not initially required.