They are wet application.
Here's a video guide.
Some tips.
* Ensure that the surfaces are scrupulously clear of all dust particles - even the most minor of particles will look like a pimple once covered
* Ensure your hands are always wet
* Use sufficient liquid but don't overdo it, otherwise you'll simply spend ages trying to squeeze out the bubbles
* Do not use more than the recommended amount of detergent, especially on clear decals, otherwise, it can have a detrimental effect. A gentle detergent as shown in the clip is better than a strong detergent like washing up liquid but you can use the latter at a lower strength.
* Sometimes it can be difficult to start the peel of the backing layer - use a razor blade to gently pick at the backing layer
* Start from the inside of the decal space to the outside
* Wherever possible, work the decal with your fingers rather than an implement - leads not only to better results but is less likely to damage the decals. Have a couple of clean microfibres to hand to not only clean your fingers occasionally (then rewet) but also helps as an implement. If you do use a plastic implement make sure it has a soft protective covering (as per clip). You can buy these with felt strips on.
* Don't rush. So long as you have the correct detergent strength and a good initial amount of liquid you have a surprisingly long amount of time to adjust the decal and remove bubbles
* When doing the move tricky bits, like folding around curves, just be patient in teasing and coaxing the water out - sometimes it seems that you'll never be able to get the decal to sit properly, but it will eventually - the decal will begin to set as you work around the piece and coax into position
* Only apply heat to finish off, once you are happy with what you have.
* Revisit your decal 10 mins after having applied - you may find the odd bubble has appeared, but you should still have time to work it out
* Can't stress this highly enough - don't try doing all varios in one go. Do one, take an hour over it, and then step back for a rest. Even per vario, if you've had a tricky time with one particular decal, just take a step back for a while! Treat it as a learning curve.
nb - photo is of the signature custom designs version of these.