Translations:AY Honors/Ultralight Backpacking/Answer Key/81/en

Here are some types of mattresses that are popular among ultralight trekkers/climbers:

1. Air pads: These mattresses are filled with air and usually have valves to inflate and deflate them. They are lightweight and can be compressed to a very small size, making them ideal for ultralight backpacking.
2. Foam pads: Made from lightweight, durable foam material, these mattresses require no expansion and are often less expensive. However, they can be a little bulkier when folded compared to inflatable mattresses.
3. Self-inflating mattresses: A combination of a foam mattress and an inflatable mattress, this mattress inflates itself when the valve is opened. They offer a balance between comfort and ease of use.