Brace height.

[mully]

The distance from the ground one should hang the partridges to prevent one's cat from eating them.

I'll get me coat...

Stephen

[Furface]

Surely you mean the distance between your kisser button/string and your teeth, sufficient to prevent impromtu extractions when things get tangled up.

[celticjedi]

The distance the barman must stretch to fill a hip flask from the optics