To date there have been eight different types - but only five of these are available solely as containers. The other three come with flat cars made by associate company Beijing Wanxuda Railway Equipment. The 20' containers come 4 to a box, and the 40' containers are in pairs - although I know some sellers who sell (sold) them individually. There is however only one road number for each of the different types.
One of the best things about these containers are the boxes they come in. I don't really focus on boxes in my reviews, but these ones are good enough to hold brass models so deserve a mention. They are a two-piece paper coated cardboard affair with the details on the top part. Inside there is a yellow felt material (some have silk) and a pair of red ribbons to easily remove the containers from the boxes.
The casting of the containers is relatively very good. The details are sharp enough, and they should be more or less compatible in stacking with other containers made by different modelling companies. The lettering is very nice and is on the container sides and ends. The size is perfect - and a single 40' or a pair of 20'ers will happily ride in a Bachmann C64 gondola. The only real problems with these containers is quality control. Many of them have minor casting defects, such as the bottom plugs missing or the top plug holes filled in. I've even got one with a piece of hair or fibre under the paint. A few of mine have paint issues, one has only been given a single coat of paint which makes it a much lighter blue - and another has the correct blue with only a single coat of white for the lettering which is very pale in comparison to the others!
There was a re-run of these containers about a year after the initial release, and were identical in every way. For Chinese modellers, these containers are a very valuable accessory and would fit into almost any Chinese layout.