Canvas backpacks rarely get this good. This classic look comes standard from the Czech Army with two massive external pockets measuring 7" wide by 8" tall and 2" deep. Packs are in great shape.
Those pockets and the main compartment all secure tightly with a strap closure. The pack itself measures 16" x 16" and 4" deep at the base. There is a separate inner compartment spanning the width of the pack as well as a drawstring closure up top beneath the lid.
The detachable straps are part of a larger system and can easily be fitted permanently with carabiner clips, zip-ties or paracord. Shoulder straps are functional, but show use and can easily be replaced with your own straps.
See the images for set-up. The color may vary as shown in the pictures.