WIll be what I see on screen in preview 100% identical wilt what I will receive as hard items?

Any monitor display in different way colours. Red is red and blue is blue but blue on two monitors looks a bit diferent.

In printing industry is different . All printers get more or less the same "blue".

The system is bulilt to be able to deliver a fast response to you as internet user. The process of generating images  mixing text with images on the fly on this website is done using low resolution images.

There are slight differences between what you see on your screen during customisation process and what you will get on your banner for example when you will receive it at your postal address.

It means:

1. Colour are not exactly the same like on your monitor.
2. Images you have may be not in exactly the same position.
3. All general layout may be slight different .

All together your hardprint will looks like what you see on screen and the quality will be better. It happens beacuse what it is generated as preview is like a draft. It gives an idea of what you will get and nothin more.