The 4 entry crab traps are legal in NSW (1 per licence holder). Not sure about other states.
In the Port Stephens area they work well for blue swimmer crabs.
Normal price of $29 is a little steep, but four for $50 is a bargain.
BCF indicates that this device is legal to use in QLD & NSW only.
Please check your state government website (for aquaculture or fishery regulations) on permitted fishing devices.
Nice find cheers