This >>>http://www.carcareproducts.com.au/product/wolfs_chemicals/nano_glass_sealant_glass_guard is what they use or very similar. Save yourself $240. Ps It will not last for 7 years.
Will that work on shower screens?!? Does it actually work to keep the glass clean?!
Yes and Yes. For best results you'll need to get the shower screen really clean first and reapply it every 6 months or so.