The ripstop weave uses reinforcement threads about every ¼ inch, creating a box grid so that if there’s a rip, it stops at the edges of the box. Ripstop fabrics are used for all manner of resilient working fabrics, from sails to jujitsu robes to ejector-seat parachutes. CPO stands for Chief Petty Officer. CPO’s are thin enough to wear as a shirt yet thick enough to double as a light jacket. We went full naval on ours — with the double, flap-style front chest pockets.