X86-Secret : ES Zone
Pentium 4 1.50 GHz ES  (Week 37, Year 2000)   
INTEL CONFIDENTIAL - QAQ1ES COSTA RICA - 3037A579-0199 - 80528PC1.5G0K - 4037A638

Only two qualification sample of the Willamette B2 stepping were released : QAQ1 at 1.5 GHz and QAQ2 at 1.4 GHz. Here is a sample of the first one. It includes 256 KB of L2 cache and is virtually identical to the SL4SH that was released as a production part.