Oxidant cream suitable for hair dye 

V: 150 ml

6%

A hair developer is a hydrogen peroxide-based cream or lotion that's used to lighten hair. When combined with hair dye, it helps the color molecules penetrate the hair shaft so that your color will be long-lasting and uniform.

Developer opens the cuticle of the hair and activates the bleach so that it can lift pigments from the hair.
The choice between a 20 and 30 Volume developer hinges on your desired lift. A 20 Volume developer provides a lift of 1-2 levels, which is great for subtle changes and gray coverage. For a more significant lift of 2-3 levels, opt for a 30 Volume developer.
For a more intense color, opt for a 1:1 ratio—equal parts of color and developer. If you want a more diluted shade or need to cover gray hair effectively, a 1:2 ratio—one part color to two parts developer—is recommended.

can developer damage your hair? Yes. Developer can damage hair. If you pick a developer that is too strong for the hair texture of your client, it has the possibility of lifting the cuticle so much that it can't be smoothed back down.