These are TWO PART Heart Shaped Refrigerator Magnet Sublimation Blanks.  You get the MDF hardboard heart and you also get a heart shape self adhesive magnet you put on AFTER you sublimate.
 
Why is this better? Many companies will sell you a 1-piece all in one MDF/magnet back combo. The problem with this is that when you heat a magnet, it loses its strength and can often de-magnetize. We prefer 2 separate parts so you can just easily place your magnet on like a self adhesive sticker AFTER you heat press your heart has cooled.
 
2" long. 2 3/8" wide.
2 parts: Hardboard heart and a self-adhesive magnet you add on after you sublimate
FRONT SIDE HAS A PROTECTIVE FILM YOU MUST REMOVE BEFORE YOU SUBLIMATE 
 
Directions to sublimate:
Remove the protective film on the front of your magnet before you sublimate
380 degrees for 60 seconds. Light/medium pressure
Cover your artwork with butcher paper
Adhere your magnet to the back of your hardboard shape after it has cooled