So you just got another shock, supposed to be better than your other shock. The thing with buying a used shock is that is doesn't come served on a silver platter. Incomplete component is common. Manuals are hardly exchanged. So, you browse thru the net to get info on how to set the proper sag for your shock. After hours of painstaking Googling, you finally managed to find the manual. Relieved...but then you discover that your shock does not have the rubber thingy that's supposed to act as your sag marker.
You have other ways to mark the sag. Mark the sag with a whiteboard marker, then use measuring tape or ruler to measure your sag. Then use a rag to wipe off the marking. You'll let out a yell when you find out that you have accidentally used a permanent marker instead. Luckily, your stash of thinner came in handy when removing the marking made by the dreaded marker.
You can order the rubber O-ring from your shock manufacturer who is thousands of miles away and they too, are very glad to give you for free but you'll have to bear the shipment cost which turns out to be equivalent to 20percent of the amount you paid for the shock.
So what do you do? Improvise...Pay a visit to your local hardware store and find a suitable O-ring that could fit your stroke nicely. I found mine at Ace, Melawati. Not just one O-ring but plenty...for only less than RM3.00.