From my experiences it is clear that single gas lasers outlive mixed gas lasers by an incredible amount. Colleagues here are still using an argon laser from the beginning of the decade, on a system that is heavily used daily. On my system I am on my second argon/krypton laser, the system having been installed here in mid 1994. The engineers pointed out that a mixed gas laser would probably not last more than 2 or 3 years sat on a shelf .... Anyway, I'd suggest setting aside stlg6000 or so for a refurb on your new laser within 2 years. Andy Andy Hubbard. Confocal Microscopy Technician, CMHT., Hodgkin Building, Leicester University. Tel: 0116 2525625, email: [log in to unmask]