When choosing a sleeping bag, it's important to consider the time of use and the prevailing conditions. The sleeping bags on the market can be divided into three different categories according to their temperature.

• Summer sleeping bags: Recommended for use from late spring to early fall. This is why the term "two-season sleeping bags" is also used.
  
• Three-season sleeping bags: Use from early spring to late fall, and mild winter.
  
• Winter sleeping bags: So-called four-season sleeping bags are generally used during the coldest weather from autumn to spring. Of course, nothing prevents you from using a winter sleeping bag even on cold summer nights.

The thermal ratings of Halti sleeping bags are tested and measured according to the EN13537 standard. This standard is followed by almost all well-known sleeping bag manufacturers, so it is easy for the consumer to compare the options of different brands. In the standard measurement, the person wears an underlayer and a beanie.

• Comfort (women's value) is the lowest temperature at which (standard woman 25 years old, 60 kg) sleeps comfortably at night.
  
• Limit (men's value) is the lowest temperature at which (standard man 25 years old, 70 kg) sleeps for eight hours without waking up to the cold.
• Extreme is the temperature where (standard woman 25 years old, 60 kg) might feel hard
  coldness. At this temperature, the sleeper is at risk of hypothermia.

However, it is worth noting that each person feels the cold differently. A person's head gives off a lot of heat, so protecting it with a hat has a significant effect on keeping the body warm. An inexperienced person sleeping in a tent can also choose a sleeping bag that is a degree warmer, because especially on short trips, the human body does not have time to get used to the cold.

When purchasing a sleeping bag, you should also focus on its size. The temperature classification mentioned earlier is best achieved when the sleeping bag is neither too tight nor too spacious. In order to guarantee optimal insulation of the bag, we recommend fitting it before making a purchase decision. Halti sleeping bags can be fitted easily, for example, in our own stores. In our sleeping bag collection, there are generally three different sizes available.

• F model: Person's height less than 175cm.
• M model: Person's height less than 185cm.
• L model: Person taller than 185cm.
• XL model: The size found in the Halti Family sleeping bag series for those who like a roomy bag. The XL size sleeping bag can also be used during winter on top of another sleeping bag as additional insulation and warmth.