21 12 7V bsi?

Hello!

Our S351-22 or S390-22 look like good matches for what you show here. You'll need to measure the balance's bottom fitting as shown below to see which one is best for your repair. Your 2112 stamp is a little odd, however. We don't have a 2112 strength option so you will have to weigh your sash and refer to the chart under the product description on the S351 and S390 store pages to determine the appropriate option for your balances.

Comparison of the S351 and S390 balance shoes.