RPM is the acronym used for revolutions per minute. It measures the number of revolutions completed in one minute around a fixed axis, giving the speed of a mechanical component. It is commonly used to describe the performance of automobile engines.
Like most ballparks built from the 1990s onward, Safeco Field is a 'retro-modern' style ballpark that incorporates many of the features of ballparks built in the 1950s and earlier with modern amenities.
As you might expect, the security around Fort Knox is very tight, with some people even speculating that the vaults are actually empty (!). The vault was built in 1936 in Fort Knox, Kentucky, in order to hold all of the gold collected from President Roosevelt's Executive Order 6102.