Do they come as a pair or just single?
This is a single damper system, designed to reduce the weight of the tailgate on descent but doesn't make the tailgate lighter to lift.
This kit reduces the weight on the tailgate and makes it lighter to lift also: https://www.truckman.co.uk/two-way-tailgate-damper-lift-assist-kit-nissan-navara-np300-2016-onwards-820trlnid41