f-stop Ultralight (UL) packs are more compact than Mountain Series packs and offer a solution when nimble will be important. These camera packs are designed for camera gear and kits that are not very heavy, up to 7kg/15 lb., because they do not have heavily padded shoulder harnesses are made of ripstop nylon covered with 120 DWR coating, while the Mountain series have a 420 DWR coating. The UL series are designed for shorter day trips and weather conditions that are not very harsh, while the Mountain Series can be used for longer trips and can be exposed to light rain for a small amount of time. The UL packs are meant for a camera gear that is not very heavy, up to 7kg/15 lb. The biggest ICU that is recommended for the UL packs is the medium sized one, because of weight limitations. Both series have a harness system that is designed to help you better distribute the weight on your shoulders and waist. The 3 biggest packs from the mountain Series have extra padded shoulder straps that ease the weight on your shoulders. They also have an internal multipurpose sleeve that can fit up to 17’’ laptop, while the rest of the packs can fit a 15’’ laptop.