Here's an example of a similar but different indicator weight.

http://shopping.yahoo.com/789923598-pressure-cooker-09914-pressure-tru-indicator-regulator-weight-9914/

The little dum in the middle rises as pressure increases, revealing alternating black and white stripes. One white stripe - 5 psi. 2 - 10 psi. 3 - 15 psi "cooking range".