Henderson Ultra 150 Mk2 Garage Door SpringWhen replacing garage springs, it is recommended to replace both springs at the same time, to ensure the spring tension and door remain balanced. Henderson Ultra 150 Mk2 garage door spring replaces Ultra 140 Mk 2. Suits Ultra 140 & 150 Mk2, double Dolphin doors over 14'6" to 16' wide, Classic 1470, Single skin GRP 7066 7070 doors. If you require the hooked end adjuster bolt, please select this by clicking the tick box when adding the spring to your