Intel i486 DX2/66
A late DX2/66 (40th week of 1996). In late '96 486 at 100, 120 or 133MHz were considered low-end and Pentium's at 100 or 133MHz were commonplace with 166MHz being the top model.
An interesting twitch of this CPU is the indication of the model number. Every 486 has an indication of it's type and speed seperated by a dash, except for this particular CPU. On the CPU it says DX266 rather than DX2-66.