This.
I have the Sigma non OS (2007 model) and paid about £350
second hand. Love it, great lens, still very sharp.
When I was looking for a Sigma I contacted the company to ask about the different versions released, here's what I came up with, hope this helps.
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1998 Sigma launches the first EX designation lenses.
70-200mm F2.8 APO EX
70-200mm F2.8 APO EX HSM
(not compatible with D3100 etc)
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Announced Friday 20th May 2005
70-200mm É2.8 EX DG HSM
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Announced Sunday 26th February 2006
70-200mm É2.8 EX DG Macro HSM
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Updated version of the 70-200mm, Announced December 2007
70-200mm É2.8 EX DG Macro HSM II
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Announced February 2010; stabilised and completely new optical arrangement.
70-200 F2.8 APO EX DG "OS" HSM
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EX - Excellence
DG - Lens Coating
HSM - Hypersonic Motor
OS - Optical Stabalization
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