Hickory Springs replacement spring for trundle units, rollaway beds sofa sleepers, and more. Use these to restore your old sleeper sofa instead of replacing it. This spring runs along the head and foot of the mech. The little hook is 0.5", the big hook 0.6", and the spring has a diameter of 0.6", with 15 coils. The total length of the spring is 2.6" so use these measurements to see if this is an appropriate replacement for your sofa sleeper's springs.