What does BIR stand for?

BIR stands for "Built-in Rigid"

How to abbreviate "Built-in Rigid"?

"Built-in Rigid" can be abbreviated as BIR

What is the meaning of BIR abbreviation?

The meaning of BIR abbreviation is "Built-in Rigid"

What does BIR mean?

BIR as abbreviation means "Built-in Rigid"