Talamex 4mm forged shackle with captive pin 8x16mm -Features two threads : one to introduce the pin into the shackle, and the second to close the shackle. When you open the shackle, the pin drops onto the second thread.The only possible way to remove the pin is to unscrew it completely, Features two threads : one to introduce the pin into the shackle, and the second to close the shackle. When you open the shackle, the pin drops onto the second thread. The only possible way to remove the pin is to unscrew it completely, hence a very limited risk of losing the pin.