This is the Lumicon 1.5A h-alpha filter system used to view solar prominence. It is about 3 years old and comes with the instructions, etalon filter body and 72mm ERF pre-filter. It wants a 2" input and a 1.25" output. There has been a modification to the body to allow a small amount of additonal tilt over and above that originally provided. The condition is excellent and I used it as recently as 2 weeks ago. The performance is superb.
$575 OBO shipped in the US.