With Tom Manning's permission, here's another offline input this subject: QUOTE The Attwood gas springs have a small amount of oil in the cylinder. If the cylinder is mounted at the top, the oil acts as a bumper that slows the last inch or so of the opening action. If the rod is mounted at the top, the oil has no effect on the action of the spring. My engineering suspicion is that with the cylinder mounted at the top, the oil will also keep the rod seals lubricated. UNQUOTE Regards, Mike Loy