Here is what Bushmaster has to say about it:
"Introduced in '94 and manufactured only by Bushmaster - this 16' Barrel configuration features full length handguards with aluminum heatshields to dissipate heat quicker than any other model. The front sight is placed so as to obtain the full sight radius designed into the M16A2 sight system. The Dissipator barrel is hard chrome lined in both bore and chamber"
This upper is in excellent condition. It comes complete with bolt and charging handle. Here is what it looks like:
$425 plus shipping.