3.5mm to 6.35mm (aka 1/8" to 1/4") adaptor cable. But wait, it's MONO! We carry these because they are useful for connecting 1/4" contact mics (or whatever weird 1/4" thing you want to try) to the 3.5mm jacks on our Makrophonie triple preamp/distortion module. They're just handy to have in your gig bag, though, so grab a couple.
Length: 15cm (~6")