Lexmark
40X3944
is compatible in the following Printer Models:
Lexmark Paper Handling
X85xe, X86xe, W840, W850 Finisher-2/3-Hole (7500-FIN)
X85xe, X86xe Booklet Finisher-2/3-Hole (7500-FNB)
C935, X940e, X945e Booklet Finisher (7510-FNB)
C935, X940e, X945e 3500-Sheet Finisher (7510-FNS)