Wow...they were hard to find! Took me two days.

Of course, they were in plain sight...still in boxes, in use as feet for a Garrard 301 turntable I'm working on.

What a retard, huh?

This is for Martin Sound PC-5308

Small aperture is 1.5" not 1.4"!! 4 bolt pattern on 4" circle, look to take a 1/4" bolt.

Wide aperture is 2" 4 bolt pattern on 4" circle and the holes are THREADED. Shouldn't be a problem because most horns have bolt holes rather than captive threaded studs.

Not sure of thread gauge but a click or two down from 1/4"...maybe even metric!

Length of adapter is just under 2" so the flare rate is quite fast.

From the looks of these they would be more appropriate for EV 1.5" drivers than 288s, sadly.