This is for a rare set of Monster Cable M1500 XLR to RCA Interconnect - 2 meters and in excellent condition! These are great for allowing you to use, for example, your CD player's balanced XLR outputs into your preamps unbalanced RCA inputs without using adaptors. In some cases, balanced outputs come off your DAC differently and could actually improve upon the sound quality over using the standard unbalanced RCA's. In an excerpt from the " Vintage Knob " website, a Sony X777ES CD player actually benefited in some ways sonically when using the XLR outputs simply because of how they are are directly coupled from the D/A converter:

Analog outputs are available in three flavors : RCA variable, RCA fixed or XLR fixed.
The fixed XLR are directly hooked to the PULSE D/A chips : very tight, very "direct".
The fixed RCA are the center of the show as they benefit from Toshiba FET transistors : sweeter, lush-ness comes in.
The variable RCA have too much cabling (from the d/a board to the motorized volume pot and back) and loose a lot of finesse along the way.
Depending on your preferences and the rest of your units, you will either prefer the fixed RCA or fancy the XLR - both are equally excellent, if in a different way.