You don't need to have more than one to comply with my very laxed rules for this challenge.
The same Barlow for thirty days would be acceptable ....... it might be more fun if you took different photos of it.
I'll give you (and others) a few more examples:
You have two Barlows ..... approximately 15 times you would need to carry one of them for the 30 days. There is
no requirement for it to be your only tote for the day.
You have five Barlows ...... approximately 6 times you would need to carry one of them for the thirty days.
You have thirty Barlows ...... you would have enough to carry a different one each day for 30 days ...... but you could carry one of them ten days, sometimes carry two or more, etc.
I really have grown to love those GEC 86' patterns with the fancy bolster. I need to hunt me down one.