A super convenient item for tying thick lines on-site, which can be a hassle.
A knot gear that can be worn on your fingers to help tie up thick lines. Knuckle shape makes it easy to tighten the hook and swivel. The portability of being able to attach it to a pin-on reel is also a great feature.

Knuckle-shaped knot gear for easy tightening of hooks ...

and swivels.

Attached to pin-on reel