5.5"X8.5" - 2 Parts / NCR - Carbonless (Carbonless -NCR products)
Carbonless paper is designed to produce instant copies of a document as it is being written on. It does not allow for a post-printed copy, but it allows to produce a copy in real time.
Carbonless copy paper is a type of custom coated paper where the pressure applied when writing on one sheet of paper generates an image on the next sheet.
Carbon copies used to require a carbon sheet in between the two sheets so that the marks would be reproduced on the next sheet.
The carbonless technology substituted the carbon copy sheet with a chemical coating on the bottom of the sheet on which you write, and another chemical applied on the sheet where the copy is to be placed.
By Юкатан - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=23177071
Carbonless paper is used in muliple applications that go from medical forms, invoices, record-keeping documents, inventory control, repair shops, car repair shops, job orders and many more applications, prescriptions, and many more applications.
Although digital forms have replaced some of the phisical ones, connectivity, technology and other factors still keep this option very current