SMALL BOX SIZE - The internal dimensions of the stackable cardboard boxes are 5 x 5 x 2 inches (LxWxH), and the external dimensions are 5.5 x 5.2 x 2.04 inches; LIGHT-WEIGHT YET STURDY - The box mailers are made of 32ect E flute cardboard, which is light-weight(only 1.55 ounce) yet sturdy for shipping mailing small items, perfect for your online business shipment; FLAT PACKING - the 25 pack of black box mailers are shipped to you in flat packing, which can save your storage space; EASY TO FOLD - The corrugated boxes are easy to put together in seconds, the tuck top has two locking taps to closure boxes and keep them secure during shipping; ELEGANT FOR BUSINESS - The outer packaging boxes are in black paper, you can stick your own labels, stickers, ribbons on it, which is very elegant for your business or small gift packaging; SMALL BOX SIZE - The internal dimensions of the stackable cardboard boxes are 5 x 5 x 2 inches (LxWxH), and the external dimensions are 5.5 x 5.2 x 2.04 inches; LIGHT-WEIGHT YET STURDY - The box mailers are made of 32ect E flute cardboard, which is light-weight(only 1.55 ounce) yet sturdy for shipping mailing small items, perfect for your online business shipment; FLAT PACKING - the 25 pack of black box mailers are shipped to you in flat packing, which can save your storage space; EASY TO FOLD - The corrugated boxes are easy to put together in seconds, the tuck top has two locking taps to closure boxes and keep them secure during shipping; ELEGANT FOR BUSINESS - The outer packaging boxes are in black paper, you can stick your own labels, stickers, ribbons on it, which is very elegant for your business or small gift packaging;