91400B Lock Down Tool The SP Tools 91400B-LDT Valve Spring Lock Down Tool is another innovative accessory for an existing tool that improves performance and efficiency for technicians making the most of every minute on the job. It was developed specifically to aid the technician while sing the 91400B, which bolts to the cylinder head and simplifies the process of removing and re-installing valve springs. In operation, the Valve Spring Lock Down Tool keeps the valve spring and retainer compressed for hands-free removal and installation of the valve keepers. It improves productivity, reduces project time and makes servicing vales much easier 91400B-LDT