I think fairly often our customers have a hard time deciding whether to order thin Ptil Tekhelet or thick. Obviously it's a harder decision when you can't see the strings up close.
Today we received the following question from a customer who was unsure which Ptil Tekhelet strings to buy.
two question on the techelet tzitzit sizes:
1. Which size is more popular, the thick or the thin?
2. Can you email me or post on the website photos of both sizes of tzitzit next to a person's hand or similar object, so I can see the size difference?
Somehow I never thought of such an obvious solution as a photo with a recognizable object alongside.
As a general rule, people put thick Ptil Tekhelet on a tallit gadol (i.e. a tallis worn to shul) and thin Ptil Tekhelet on a tallit katan (a garment worn under the shirt to observe the mitzvah of tzitzit all day. But there are certainly plenty of exceptions to the rule. It's really a matter of aesthetics and personal preference.