Model J Vertical Lifting, Locking The Model J is a vertical lifting clamp capable of turning a single plate or member from horizontal to vertical and back to horizontal through the same 90 degree arc. An Application, Operation and Maintenance Manual is packaged with each Renfroe® product. Repair Kits are also available for most Renfroe® lifting clamps. We encourage caution when using lifting devices. Refer to the Operating Aids section for important handling information.