Some drill chuck key sizes available include 1/4 inch, 1/2 inch, 5/8 inch, 1/8 inch, 5/32 inch, 3/8 inch and 17/64 inch. These types of keys are used to tighten and loosen the chuck grips that hold drill bits into the drill.
Most drills that have a keyed chuck assembly come with the key that is required to loosen and tighten the chuck. These are easily lost since many of them do not come with any sort of holder or attachment to the drill itself. Chuck key holders can be purchased as well as replacement keys. The holders that can be bought also give extra torque when tightening or loosening the chucks because of the bar style they are normally available in.
There are packs and multi-sized key chucks available also. This can make it easier to keep all of the chucks in one place for multiple tools. It also comes in handy if the size of the chuck needed is unknown. The multi-sized chucks are normally in a cross shape with four different sizes on each device. The packs are normally display refills or actual displays, but can be bought for personal use as well. These normally come in a variety of sizes. Other drill chuck key sizes available include 7/32 inch, 15/64 inch and 9/32 inch.