Transfer films such as the HappyMask are required for "transferring" self-adhesive films such as HappyVinyl or printable films such as HappyPrint Dark. These films are cut with the "good" side facing upwards and the carrier is on the adhesive side. The transfer foil ensures that all the individual parts of your transfer remain together and in the correct position. Transfer foil can be used multiple times as long as the foil sticks strongly enough.
The HappyMask Vinyl sticks slightly stronger and is therefore very suitable for transferring the robust HappyVinyl films.
For the thin HappyPrint Dark we recommend the HappyMask.