E-Series and M-Series inverted screw jacks with bellows boots must incorporate an allowance in the length of the lifting screw for both the closed height of the boot and structure thickness. Since Power Jacks can make no provision for attaching a boot on the underside of the customers structure, Power Jacks suggest that a circular plate similar to the lifting screw top plate be welded or bolted to the bottom of the structure supporting the screw jack, thereby making it possible to use a standard bellows boot. (refer to E-Series Screw Jacks brochure (P60)). S-Series cubic screw jacks allow mounting from two sides instead of one and allow mounting on the same side as the bellows boot with only an access hole required in the structure for the lifting screw and bellows boot.