To customize the TTL (Through-The-Lens) loupes to match your personal traits, we will need your pupillary distance (PD) measurement. It is just a measurement of the distance between your pupils:
The PD can be measured by any local optician (Costco, Target, Wal-Mart, etc) by using a pupilometer that every optician has. This service is usually free
20% restocking fee for all customized TTL loupes
Case included with each pair of loupes
Manufacturer’s product information (ultralightoptics.com, opens in a new tab)