Box Stays

Screw mounted to side panel and lid
Non-handed design
Spring holds lid in position
For heavier lids 2 stays should be used
Distance B should not be less than 85mm

By selecting screwing dimensions A & B, different lid sizes can be adjusted to an optimum
The weight of the lid is not the relevant measure, but the moment
Moment is calculated as follows:
Lid weight x (0.5 x lid depth) = moment