Wise Men Company works with IC13 Arms to make their Signet Rings. Somewhat like the Thyrm Swithback adds a ring to a flashlight, the Signet adds a ring to your Spyderco. The Signet Ring is a replacement for the backers of Spyderco Delica 4, Endura 4, and the Matriarch 2.
It is machined from aircraft billet aluminum and anodized black. It works great when used on a Spyderco knife with the Emerson Wave feature however the Zip Tie Spyderco Hack will accomplish the same goal.
For those not familiar with the Zip Tie mod, watch this video.
Depending on where you position the pocket clip you can draw the knife either hammer grip or karambit grip. As shown in the video below.
Installation is rather simple.
The signet ring retails at $30 for the Delica model and $35 for Endura or Matriarch. They are working on designs for the Spyderco Paramilitary 2 and while there are requests for the Kershaw Emerson line, they are not sure if people who buy such low cost knives will buy a $30+ accessory. If demand is high enough they will meet that demand.