What nails/staples can I use for Westcott ProjectMate Multi-Purpose Staple Gun #16703?

Westcott Staple Gun, Item 16703 is compatible with the following readily available staples:

Westcott item 16704 available online on our website.

Any Stanley TRA series staples available online or at Home Depot or Lowes.

Any Arrow JT21  available online or at Home Depot or Lowes.

It will also fire 18ga brad nails available online or at Home  Depot or Lowes.

Please see below for diagram on inserting brad nails: