ABS, permalloy, copper, PVC, and carbon film resistor
1 x 1 x 5/8" (2.5 x 2.5 x 1.5 cm)
Square, Inc., USA
Square is a tiny attachment that can be plugged into the headphone jack of a smartphone or tablet to allow anyone to accept a credit card payment. The card is slid through the attachment; signatures on touch screens stand in for printed receipts. This simple idea is as efficient and potentially transformative as designer Jack Dorsey’s previous big idea: he is one of the co-inventors of Twitter.