Are you sure this should not read 4x5 inch filters? If these are indeed circular filters, I can only think of a Panavision matte box that would accept it (circular 4.5" and 138mm filters are a classical "feature" of Panavision camera accessories...)

"4.5 inch round" aka: ' 4.5" round ' is a standard size made by Tiffen and was a commonly used round size in the rear of certain matte-boxes (Chroszeil come to mind http://www.chrosziel.com/prod.asp?wdid=36&pid=74&sid=0 ) and also used with rubber sunshades and step up rings, when no mattebox was rented, this was usually to save money and the lens was usually a 16mm Angenieux or Cooke zoom. The commonly used round sizes for small professional lenses (Zeiss super speeds T1,3 and reg T2,1 series) were "Series 9", the next larger size used was "4.5 inch round" and the next larger commonly used was 138mm round. Don't ask me why 3 different sizing nomenclatures were used. It's just the way it was, so you learned to deal with it.

When the Canon 8-64mm T2,4 was introduced it came with it's own custom 4x4 clip on matte box. Around the same time Arri released the LMB-3 and LMB-4 for 3x3 and 4x4 filters, with a ring for the 80mm wide front lip on the zeiss lenses (mentioned above). Rental houses would machine out a ring to fit the popular competing Zeiss 10-100 T2.0 zoom). Since 4x4's could also be used in a matte box, the round filters lost favor as soon as the production could afford a better zoom and a matte box (evt. a filter package too). However since Diopters only come in round sizes, 4.5" round still had some place. The rental house I worked in the late 80's definitely had them, I don't know how widely used they are today.

The round filters were great for run and gun doc shooting where you just needed nothing more than a color balancing filter (85) or Pola or ND. Stacking more than 2 usually resulted in vignetting on your only lens (a zoom). We're talking docs shot on film, before the advent of the cheap video camera, which I think arrived in the mid 1980's. aka: ancient history compared to what we have today!

I know that Tiffen made a 72mm to Series 9 ring. And a Series 9 to 4.5" round ring. The problem is that once you get away from the cheap photography accessories and into the pro motion picture ones, the prices go way, way up.

This is the normal price: http://www.bhphotovideo.com/c/search?Ntt=series+9+step+up+ring&N=0&InitialSearch=yes&sts=ma&Top+Nav-Search=

This was a deal: http://www.ebay.com/itm/Tiffen-Series-9-9WA-Metal-Lens-Shades-a-72mm-Adapter-Ring-and-Boxes-/251376365429?nma=true&si=v5zGfyc0bxBTZDTPzlspJMQgk1E%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

So at B&H you will spend ca. $190 on 2rings to go from 77mm to 4.5 round. Them you still need a sunshade. Sometimes people with bigger cameras are selling this stuff used: Reduser.net, CML sales (google it), and less often does it come up on ebay, I think. Schneider listed an 82mm to 4.5" ring for $195 https://www.schneideroptics.com/ecommerce/CatalogSubCategoryDisplay.aspx?CID=1641

In a pinch you can also tape a filter onto your lens.

I bought some series 9 filters years ago when I found some 52mm and 72mm to series 9 rings on deep discount once. The filters I bought used at B&H, when I lived in NYC, every time I was there I'd check with the used dept. I rarely use the filters and won't buy any more.

Unless you already own a matte box that can take 4.5" round in the back, I am not sure why you'd want to buy this filter size?

Thanks a lot, it is true that with the adapters the price does sky-rocket.