Turbo Tweak Alky chip for 50s

[Sweet6]

Version 5.5. 23/21 degrees timing. But is also adjustable. +/- 4 degrees. I bought this chip new last year. $50 shipped/best.

 

[Sweet6]

Ttt

 

[92TCC]

Chip

I don't know much about the chip. I am interested. I need some more info. Can you tell me how to change the timing around? I don't understand the -4 +4 degrees?
Tom

 

[Sweet6]

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