Gas struts have to exactly match the model number due to different gas strut pressures weight dependant if you are unsure at all please, check your serial number on the back of the bed on the manufacturers plate, or what's app (07785246539) the picture of this or email. 

These gas struts are to suit the Hapro lumina 36.c.sli and other 36 series such as the 3603 
We always advise swapping these in pairs, As swopping just one could create inbalance if the existing gas strut is slightly weaker. Any questions please dont hesitate to ask 

2 gas struts in a pack.