Thai people also use the Chinese style wooden steamer shown above. This is widely available and comes in a variety of sizes. The one show above is available in 3 or 5 layers, and fits on a regular 22cm (9 inch) western boiling pan.
This style of steamer is used for larger items, chinese dishes like dim-sum and for steaming fish and even chicken legs. It's not suitable for rice steaming, as the slots are too wide and the rice falls through, for that use the Thai steamer.
Clean it with water and washing up liquid, these are not suitable for cleaning in a dish washer because the wood soaks up the corrosive chemicals.