This bed hardware is used for knock-down frames but fastens with bolts instead of hooks or tapered connectors. Though the brackets require more clearance than other styles (for the bolt mechanism), they cannot be accidentally dislodged.
The low-profile set has a height of just over 3 1/2", and mounts with seven #6 screws per corner.
The regular set has a depth of just over 3 3/4", and requires eight #8 screws per corner.
Both sets are zinc-plated steel and are sold in sets of four. Screws not included.