The snap shackle with swivel catches slightly when locking into place.
The snap shackle I ordered, already tied with a halyard knot, arrived at the Kiel shop in a brown paper wrapping (not a plastic bag with a hanging loop and type). It's a bit stiff, which I intend to improve with some sanding and silicone spray, given the effort involved in replacing it. The shackle attached to the spinnaker halyard kept popping open from its original position on the turnbuckle because I hadn't noticed how stiff it is when locking into place.