Can someone tell me what this is? (Comb Filter)

Can someone tell me what this is?

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=006

and the info for it is here:

http://www.leitch.com/custserv/produ...a!OpenDocument

i know it is a comb filter, but i did not understand it completely, and again i was hoping someone here might understand it?

is it a great Comb Filter but out of production or something?