Abstract: The present invention overcomes the drawbacks associated with earlier top designs by providing a rigid frame at a sufficient height above the boat to permit persons to move about comfortably beneath it. A flexible cover is suspended from the frame and is held taut by the frame. The flexible cover is attached to the frame with sliding connectors. The cover may be moved between an open position and a closed position by sliding one end along the frame. In the "open" position, the cover is folded back in accordion folds against one end of the frame. When slid "closed," the cover occupies nearly the entire surface within the perimeter of the frame. As the flexible cover is suspended between opposing frame members, it will remain taut and free from flapping even when the boat is traveling at high speed.

Abstract: An internal combustion engine spark plug provides an overpressure release mechanism to avert engine component damage as a result of hydrostatic lock caused by liquids (typically water) entering the combustion chamber under operating conditions. This spark plug incorporates predictably and adjustably weakened structural zones such that, upon encountering overpressure situations, the central portion of the plug is ejected, generating sufficient flow area to expel gasses and liquids from the combustion chamber and venting the cylinder to the atmosphere. The invention is also useful in the detection and avoidance of damage under conditions of detonation.

Abstract: The purchasing system with a rebate feature is utilized by subscriber-purchasers, vendors providing goods and services, a future benefit guarantor such as an insurance company selling annuity contracts and in some cases an escrow agent. The purchasing system allows for the input of purchase orders from the subscriber-purchasers for selected goods and services and correlates the transfer of funds from those purchaser-subscribers to the various vendors selling the selected goods. In one instance, the transfer occurs between the subscriber-purchasers and the escrow agent. The future benefit guarantor supplies a rebate factor which is input into the system. The system then computes and reports a rebate which is due in the future to each subscriber-purchaser from the future benefit guarantor. The rebate is based upon cost of the individually selected goods and services and the rebate factor.