They come in 4.25" by 5.5" with matching envelopes. Each card is made with high-quality uncoated paper . 
.: Material: 271gsm uncoated paper
.: One size: 4.25" x 5.5'' (10.8 x 13.9 cm)
.: Horizontal and vertical options available
.: Available with printing on the outside and inside
.: Each card can be customized with a specific design
.: Matching white envelopes included
.: Assembled in the USA from globally sourced parts