Use my biner/pulley FS yesterday...it makes life so much easier! I made it with spare kit I had in the truck. The advantage is, each component is already designed and rated for tree work as opposed to stuff you pick up at the hardware store.
1 nylon loop sling (length optional)
2 carabiners
1 micro pulley
If you are using a Moss type tubular rope saver, its different, you are not hanging your weight on it and it wouldn't need to be rated for life support and the hardware store would be appropriate!
I was taking down some casuarinas, you must have those in Hawaii Vox, they have real shaggy bark that sets up a lot of friction running the line over a natural crotch...the FS made the job so pleasant, especially as I had to go up and down a few times, using one tree as a tie in to work on a couple others before it in turn came down.