Armor

A buckler is held in the hand, and can be equipped or dropped as easily as a weapon. The hand cannot be used for other purposes while it holds a buckler.

A light shield is strapped to the forearm, taking a full action to equip or unequip, but it leaves the hand open to perform actions, although the wielder takes a -1 to attacks on a round where he does this, and the shield doesn't provide a bonus to AC on that round, unless the wielder has the Improved Shield Bash feat.

A heavy shield is connected to the upper arm and forearm, and, though the hand is not occupied, the arm is normally too restricted to allow for manipulating objects in combat without special training (such as the Shocktrooper soldier's Smashing Grace ability). Equipping or removing a heavy shield takes 2 rounds.