When I bought online from Zenni optical they sent a plastic ruler that you set on the bridge of your nose with a slot in the middle, and can be used to measure

When I bought online from Zenni optical they sent a plastic ruler that you set on the bridge of your nose with a slot in the middle, and can be used to measure PD. It's similar to this: https://store.eyeque.com/eyeque-pd-ruler.html https://store.eyeque.com/eyeque-pd-ruler.html