What are Silver Pantaloons for?

In Baldur's Gate 2, I got the item Silver Pantaloons.

What is the purpose of this item? Is it useful or can I toss it?

Solution 1:

The Silver Pantaloons are part of a bonus item set you can get by playing the same character through Baldur's Gate 1, 2 and ToB.

If you collect these items while playing:

• The Golden Pantaloons from BG1
• The Silver Pantaloons from BG2
• The Bronze Pantalettes from ToB

After getting all three, you can have Kerrick the Smith in Amkethran combine them into the Big Metal Unit: a -10AC armor suit that anyone can wear, as well as a Big Metal Rod that can shoot 3 different kinds of ammo.

Source: Big Metal Unit guide

There's also a rambling history on the subject at baldurdash.org

Solution 2:

Here you go:

Returning to Kerrick the Smith in Amkethran, he would then forge the Golden Pantaloons, the Silver Pantaloons, and the Bronze Pantalettes, for no charge in gold whatsoever, into:

• The Big Metal Unit: A suit of armour, wearable by all characters, with a base Armour Class of -10, that gives the player the size and appearance of an Iron or Adamantite Golem.

• The Big Metal Rod: A launcher for several types of ammunition.

• Scorcher, Pulse and Frag Grenade ammunition for the Big Metal Rod.