If traveler controls are not used, you can help prevent shock-loading your rig when tacking by using a pair of #3213 Pinstops on low-beam track (with drilled pinstop holes), to localize the traveler position.
The shackle can serve as an attachment point for a block in emergencies. When used on genoa track, the shackle can be used to attach a genoa lead car, or as an inhaul/barber haul attachment point.
