Restrained spring mountings shall have an SLF mounting as described in SLF Specification, within a rigid housing that includes vertical limit stops to prevent spring extension when weight is removed. The housing shall serve as blocking during erection. Installed and operating heights are equal. Restraining Bolts shall have a neoprene bushing between the bolt and the housing. A clearance of 1/4” (6mm) shall be maintained around restraining bolts and the bushing so as not to interfere with the spring action. Limit stops shall be out of contact during normal operation. Since housings will be bolted or welded in position there must be an internal isolation pad. Housing shall be designed to resist all seismic forces. Mountings shall have an OPA preapproval from OSHPD in the state of California certifying the maximum certified horizontal and vertical load ratings. Mountings shall be type SLR or SLRS as manufactured by Mason Industries, Inc.