What price will be charged for a First-Class Mail piece measuring 12" high x 15 1/2" long x 1/2" thick and is flexible?

The reason the parcel price is charged for a flexible piece measuring 12" high x 15 1/2" long x 1/2" thick is because the dimensions and characteristics of the item fit within the guidelines for parcels. In this case, the piece exceeds the maximum dimensions allowed for First-Class Mail letters and flats.

First-Class Mail typically applies to letters that are within certain size and weight restrictions, and while a flat is designed for larger envelopes, it must still meet specific size requirements. However, the combination of dimensions provided indicates that the item is more appropriately categorized as a parcel due to its thickness and overall size.

As a flexible item, it also influences the pricing, as it requires consideration of parcel rates based on weight rather than the flat or letter rates, which apply to differently sized mail pieces. Thus, under these guidelines, using the parcel price ensures that the mail piece is classified and charged accurately according to postal service standards for items of its size and shape.