Andy 4 It was the first time to use such spring-dampeners.Finally they worked well but...I had to position and reposition until I understood just how to fix them.I used them on two desks.The first one is old and very heavy so only helped a little...The second one was on a new desk (quite light). The top opens very well if a little fast!I recommend them but expect some repositioning!!! And the results will depend on the weight of the unit.Oh! and VERY important if your desk is just hollowborad type, these will probable damage it. The springs are very strong... stronger than the desk material!!! Ripe...Overall I'm happy but I will measure & research weights next time.