Rav Weitzman said that the exact amount that could be shown is according to the "custom in each place" what does that mean? Does that mean that if i live in a certain place and everyone there wears baseball hats and all the rest of the hair uncovered then that becomes the custom of the place? is there a maximum amount of hair that is allowed to be shown according to everyone who holds halacha?

Shalom, Thank you for your question. In relation to the laws about hair covering, Rav Weitzman wrote "a woman should cover her hair and may leave a small amount uncovered. The exact amount is dependent on the custom in each place". That is – the definition of "a small amount [left] uncovered" is "dependent on the custom". So, while Jewish law requires married women to cover their hair, there are many varied, and valid, practices as to leaving a small amount showing. Some communities cover all the hair, and not even the smallest amount is left showing. In others, only the small wasps of hair that grow above the ears are left out. Then there are communities that leave out up to a "tefach" – a hands breath. Exactly how to measure this tefach is also a matter of debate. Some allow a tefach at the front and back at the same time – others only on one side. There are other practices also – such as covering the hair with a wig; a wig and a hat or scarf - and every community has their own traditions and halachic opinions. The majority of main-stream Rabbinic opinion seems to be of the opinion that one may not expose more than a tefach (a hands breath) of hair. But, as Rav Weitzman wrote, one should be guided by local community practices. I hope this is of some help to you. Blessings.