Although the description says this mount will clamp to a "tube up to 1.181" diameter," I'm using it with a Wali speaker mount's top tube (which my calipers say is 1.27" in diameter) and it's snug but fits perfectly. Very sturdy, high quality mount, just the thing to secure my cans conveniently when they're not on my head. The surface for holding headphones is almost 4" deep, and accommodates both the Bose QC25s I use with the computer, and the QC35s I use with my phone (though it's a little crowded). Other headphones (I've tried with Sennheiser HD58x Jubilee, Philips SHP9600, HiFiMan HE400SE, etc) will fit no problem.