it depends where you live in the world as to if it's legal or not, but in most country's it's not legal strictly speaking. legal the USA/Australia 40 ch AM/LSB/USB at 4watts AM and 12 watts pep for lsb and usb. FM is legal is some countries mostly European one's. however in most countries radio laws for 27mhz cb is not a death sentence and as long as your radio is not causing interference other services there are many that use big power and go outside the 40 channels, in fact pirating cb has become big business with people and the company's that supply the radio's to them, the radio you are looking at is sold as 10m or 28/29mhz radio that is meant for the 10 meter amateur radio band but is mostly used and aimed at the cb radio market, this type of radio is known as "export" radios. without going into radio science too much lets say the AM mode is 6 khz wide and has a carrier and USB and LSB is 3 khz wide in bandwidth and has no carrier and because and so is more efficient than AM because it don't have to supply power for a carrier and it's only halp the bandwidth of AM so more power can be squeezed into a smaller bandwidth making lower side band (LSB) and upper side band (USB) much better for long distance communication.
I hope this has helped you, i am sure others will help you more :0
all the best
