Posted By Paul Leadbetter I was recently shown a laser pointer pen which was labelled as Class IIIa; am I right in thinking that this is dangerously powerful for such an application? I seem to remember that, at Class II, the normal aversion reflex is sufficient to protect the eyes but that anything more powerful would cause adverse effects before the eyes could be averted. Any thoughts on this would be much appreciated. Paul Leadbetter

Posted By Jane Blunt Dear Paul Be aware that the British classification system uses Arabic numerals, 1,2,3A,3B,4 and the Americans (and maybe others) use Roman numerals I, II, IIIA, IIIB, IV. There are slight differences between them. Go to http://www.osha-slc.gov/SLTC/index.html and look up 'Laser hazards' to follow the link through to the OSHA technical manual for a description. Jane