窓付封筒ケース【サンプル展開図】

Envelope-shaped Case Featuring a Window【Sample development drawing】

Although this looks like a normal envelope case with a window, there is no actual hole in the paper. The window is made by a slit without being cutout. Thereby, making the process of filling the case a lot easier; eliminating manufacturing difficulties. 
*In Japan, these are used to gift someone with an envelope.

$10.00