Yes, they were and are all department store bikes. MGX was a name "invented" by Mongoose when they were owned by Brunswick (the bowling alley people) who also owned Roadmaster. MGX was their effort to have a middle ground between the two brands.
Interestingly, in 1999 and 2000 there were more MGX bikes sold in the US than ALL other brands combined. They were cheap and of sufficient quality that they wouldn't fall apart, at least not right away. The way they did this was by buying high quality closeout parts (like the RockShox Judy fork) from overstocked manufacturers and combining them with rather low end parts on the rest of the bike (Sunrace and Torque Glide drivetrains, etc). As the good parts were depleted they were replaced with those more akin to the price of the bike.
Most MGX had this transparent orange color applied over a brushed aluminum frame. kinda ugly in my opinion but it sold anyway.
I still wouldn't trust an MGX for anything but the most casual of riding, definitely not for (in the case of BMX) any type or racing or stunts.
