My experience was the exact opposite. My lightly used 4/600 dies after less than 100 sheet printed. I have had a lot better luch with My LaserWriter Pro 600 and 630 and my 16/600. Cartriges typically fit HP and Apple printers becasue the engine was made by Canon. I am not sure who made the 4/600 engine. Mike >I have an Apple LaserWriter 4/600 that I bought in 1995 and it's the >printer that will not die. Zero problems. Zero glitches and I've cranked out >many multiples of thousands of pages with just one perfunctory >cleaning/service. It's still my everyday printer for all my Apples and Macs, >even though I have some other, fancier and newer units on the network. I >despair of it ever wearing out.