This is a bit off topic. Hope it's OK oldhaole.

Actually those composters are among the best. Three parts right? Keys to composting are as follows:

1. Get a good balance of green vs. dead matter - think dead leaves vs. fresh cut grass.

2. Make sure you have a nitrogen additive. Like I said, piss works great. I let my kids use is as an out door toilet which greatly pleases my mother in law... You can also buy a compost accelerant but the key ingredient is nitrogen so you may as well use your own.

3. Make sure you have decent drainage. Straw works very well as the first layer but really, so long as it is sitting on dirt and not concrete you will be fine.

4. Add water. You want the material to be the texture of a wet sponge. Not soaked but good and damp. I leave the top off mine when it rains and then flip it afterward.

5. Turn the pile every 10 - 14 days to add oxygen. Add more water and nitrogen accelerant at the same time if needed. Here is where your system is so useful. Take the top section off and place it next to the other two. Now just scope the material out with a fork and place it in the empty container. Repeat until you have removed all the material.

If you get the mix right you will see an explosion in the red worm population. This tells you that the microbial activity in the pile is high which is what you want. Also note that composting will greatly slow or stop during cold periods below 40 degrees F. unless you are dealing with quantity. Also note that if you continue adding new material you will end up with bits of uncomposted stuff in your finished pile. I also use my three tiered system to segment nearly finished compost. I use two sections for the nearly finished / larger pile and one section to collect new stuff.

You can find all kinds of info on line. Run a google search.