Karabiners* for freeflight air sports: solo and tandem paragliding, paramotoring, speed flying and hang gliding. US spelling "carabiners". Karabiner is shortened from German "Karabiner-haken", meaning "spring hook"; now you know!
Karabiners should only be used for their intended purpose. Every karabiner is different. For example, those designed only for solo paragliding use should not be used to connect a tandem wing. Karabiners should not be used to connect reserve systems (use suitable maillons, soft links or direct connection - if appropriate).
Like soft links, karabiners have a limited service life. They must be inspected regularly by the owner and replaced within the manufacturer's stated replacement interval, at the latest. For standard solo paragliding use, most manufacturers state 5 years or 500 flight hours, whichever is soonest. Some state shorter, 2 years, others conditionally longer. The service life for tandem and acro paragliding, and hang gliding use is usually significantly shorter, due to the higher stress put on them. How much do you value your and your passenger's life? More than a pair of karabiners, we hope!
Read each karabiner's product description and manual, if relevant. If in any doubt, seek expert advice.