7D9887, aka "Time Slider", is a lap slide guitar with a few unique features. The most obvious of these is the autonomous bass string. It is off-set, has a slightly shorter scale-length, and considerably lower action than the other strings. The purpose of this setup is to allow the player to comfortably fret the bass string with his or her thumb while using a slide at the same location on the other strings.

Another unique feature is the mobile pickup, giving the player to an additional way to control tone. Turning the tap handle moves the pickup.

Finally, a much less less obvious feature of 7D9887 is its naïve application of general relativity to quantum mechanics -- the ability to send sound waves very slightly back in time. At the core of the instrument a heavy atomic nucleus rests inside a strong magnetic field, causing it to elongate it into a cylinder. Sound waves generated by the strings are then projected across this exceptionally dense spinning cylinder, effectively sending the signal approximately 687 milliseconds back in time. By amplifying this time distorted signal along with the signal at its creation we achieve a sort of reversed echo effect. This can be a bit disconcerting at first as the player hears each note just before he or she plays it, followed immediately by the same note as it is actually played. Under most interpretations of quantum mechanics this does not violate causality and is therefore safe for use by anyone with more than 687 milliseconds of time to kill.