Craig Biggio Bat Questions

[stdrwt11]

A few years back I bought a Biggio Game Bat that was originally a Promo bat (missing the model number H 176) from a GUU member (Thanks again!). It exhibits all the characteristics of a gamer but has unique markings with the 7 on the handle. I am just curious:

1. Does anyone know why these markings are on the handle or what they meant?

2. How often did Biggio use promo bats in games or BP?

Thanks all! I did contact Chris who knows Biggio's well but did not hear a reply on this matter.