Quick release bolt assembly included shank and head of larger cross-section than that of shank. A process for the cracking of olefins in a hydrocarbon feedstock containing at least one diene and at least one olefin, the process comprising hydrogenating the at least one diene to form at least one olefin in the presence of a transition metal-based hydrogenation catalyst at an inlet temperature of from 40 to 200\xb0 C. The present location of the driver may be manually entered into the driving directions system by the driver, or automatically determined using a global positioning system receiver. The material may help the downhole fluid maintain a relatively low density of less than about 1100 kgm3. On the top side, a dielectric layer is arranged.