In normal phase HPLC, the mobile phase is relatively non-polar and the. stationary phase is relatively polar. Other more general types of HPLC include partition, adsorption, ion-exchange, size-exclusion, and thin-layer chromatography.
This particular guitar loop pedal is the Boss RC-30. Simply put, a loop pedal is a device used to capture sound clips which are then played over and over again (looped) and often overdubbed. While loop machines have been around for quite a while, the idea of a guitar loop pedal is relatively recent. Instead of the traditional box controlled by the hands of a DJ, loop pedals allow guitarists to control the looping and overdub features via foot switches.
If you play slide or bottleneck guitar, you'll want the action higher still. In fact, if you use the slide all the time, you don't really have to use the frets, and there's no such thing as an action that's too high. Keep that in mind when you get a free guitar with a really bent neck.