This is known as a quick-link or d-link shackle.
Use instead of a standard shackle to attach the jib to the bow of the boat – never get the kite sheet snagged again
This is charmingly known as a sail slug. You will have one on the clew of your mainsail. Shackle another to the mainsail tack and slide it into the mast track. For extra marks, use a bit of shock cord to hold down – loop thru, put an overhand knot in each end and slide into the mast track breath the gooseneck