After reading Tony's reply, I now realize what your question must be about: the ventilation holes on the right-hand side. On mine, there are two, both 6.5 inches high, the front one 4.5 inches wide and positioned roughly over the third through thirteenth cards, the rear one 6 inches wide and positioned roughly over the 8th through the last slot of the second backplane unit. Both holes have a grill of hexagonal mesh, about 1/4" spacing, welded on the right hand side. Does this help? And, to be more explicit about the lips, the front and left lips are about 3/4" of an inch. And the back panel has two slots, each roughly 2 3/8" wide. I think my maintenance books might have a drawing; if I find one, would a fax of that page help? -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927