These Pro-Latch spring kits are the perfect solution to add some tension to what you are securing. More pressure is needed to engage the latching mechanism to ensure a safe connection every time. Trust these Pro-Latch assist spring kits to give you the tension that you need. Note: When using as a bonnet latch it is advised to have a secondary latch in place. QL21's are designed for the forces placed on bonnets. Other latches can be used for bonnets but multiple units (4 or more) are recommended as well as the secondary latch.