Amazon.com: STAEDTLER Ruler, 30 cm Length, Double-Sided Scale for Left- and Right-Handed Users, Made of Transparent Plastic, Ruler in polybag, 562 200 PB : Tools & Home Improvement
PD Ruler, Pupillometers for Measuring Pupillary Distance, Essential Tool for Single PD or Dual PD On-line Order Eyewear - Amazon.com