There are several reasons for the image to be blurred, here we will help you to solve the most common ones. If the following steps do not solve your problem, please contact our customer service team for more personalised assistance.
Scan the QR code
When you open either Heromask Languages or Heromask Mathematics the app will ask you to scan a QR code to adjust the resolution of your smartphone to the characteristics of the viewer. This is the QR code: 
You can scan the code from our apps or by downloading the Google Cardboard app from Google Play or App Store as follows:
- Download Google Cardboard app
- Open the Google Cardboar app and click on the 3 top right dots
- Now click on "Change viewer"
- Finally, scan the QR code shown above.
Check that the smartphone is well placed on the Headset
Make sure that the smartphone is well placed inside the Heromask as shown in the following video.
Make sure that the smartphone is well centred inside the Heromask as shown in the following image. 
Remove the stickers of the lenses
To avoid scratches during transport, there is a sticker on each lens that says "Remove before use". If you have not removed the stickers, remove them now and clean the lenses with the included cloth.
Interpupillary adjustment
Put on the Heromask and adjust your vision with the wheels at the top. The left and right wheels regulate the distance of the left and right lenses respectively to the screen, adjust them until the image is clear for both eyes. The central wheel regulates the distance between both lenses, adjust it until the vision is clear and homogeneous. These settings change for each individual.
If the above steps have not solved your problem, please contact our customer service team and they will give you a more personalised assistance for your case.