Rectangle

They offer high thermal performance thanks to their narrow design, which reduces air gaps and heat loss. They are lighter than rectangular ones due to the use of less material. Recommended for hiking, mountaineering, or extreme temperatures.

Hollow Fiber

Type of synthetic filling that offers better insulation than other synthetics (due to hollow fibers that trap air) and retains warmth even when wet. It is economical and easy to care for. However, it is heavier and bulkier than down and loses its effectiveness over time.

The warmth of a sleeping bag is determined by the fill density inside it, which is measured in grams per square meter (GSM).

350

Suitable for spring, summer, autumn

Polyester

Durable and economical synthetic fabric, ideal for the exterior or interior of a sleeping bag. It does not absorb water, so it dries quickly and withstands moisture, while being resistant to sunlight and daily use. Its main disadvantage is that it may not be as soft to the touch as other fabrics.