What is the "Set Style" button for?

What is the Set Style button for in the TF2 backpack?

Some hats and misc items have multiple styles to them. Set Style switches between them.

I'll post a list of these items shortly, as well as a screenshot or two.

These items are:

Added 2011/04/14:

• Googly Gazer
• Ghastlier Gibus
• Scotsman's Stove Pipe
• Treasure Hat
• Hat of Undeniable Wealth And Respect

Added 2011/04/20:

• Grimme Hatte (I think)
• Pyromancer's Mask
• Troublemaker's Tossle Cap

Added 2011/05/05:

• Aperture Labs Hard Hat (formerly [classified])
• Blighted Beak

Some of these are different models, some of these are just different paint jobs.

Here is my Team Spirit colored Pyromancer's Mask with the paint changes:

Here is my Ghastlier Gibus with model changes: