Hot Air Pens are limited in their use. IMHO you would be better off buying one of teh competatively priced Hot Air stations from Hakko, KADA, Aoyue, Xytronic or other similar Clone units. The nozzle sizes available will cover anything that you decide to work upon without the limitation of low power as found with hot air pencils. The '852' models are a common hot air station. A Google search will present you with many different versions at excellent prices. They are now so cheap as to be almost disposable if they fail. Heaters are a common consumable but cost less than US$10 to replace.
Fraser