Following are examples of three metamorphic rocks and a list of their uses. Marble is a metamorphic rock that is used to make floor tiles, counter tops and it is carved into statues and was used extensively in the building of the Roman Colosseum and other historic buildings. Slate is another metamâ¦.
A hex key, Allen key or Allen wrench is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head (internal-wrenching hexagon drive).
Hex key (AllenÂ®) Not equivalent to hex-headed bolt; a hexagon recess is machined into bolt head; efficient torque transfer; screws can have small or even no head (i.e., set screw); driver is cheap to produce; hex wrenches (viz., allen keys) are more common than screw or drill bits.