It is a classic workwear style originating from the United States, made primarily of moderately thick canvas, featuring a relaxed straight cut, double-layered knee reinforcement, triple stitching, and iconic tool pockets and hammer loops.
 
All cotton soft midweight canvas
Copper rivets & YKK shank button
Double front to protect your leg
Triple stitched in/out seams and back yoke
Lined back pockets with tools pocket on lower back