The XLC Adjustable Stem look just like the Sunlite one I have. I've noticed Amazon can sell the same product under different product names at different prices and shipping dates (I avoid any overseas shipper because returns to China can cost more than the product sometimes). If it is same adjustable stem, I just needed to add two additional spacer which were 2.5mm thick for each spacer for 5mm total. The 10mm spacers might be too thick and you might have to play with the existing spacers along with the 10mm ones to find the right combo.
Amazon spacer I used for $10.22:
https://www.amazon.com/gp/product/B001CJZBH0/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1
The picture is wrong on Amazon. You get 5 spacers that are 2.5mm thick for each one (you don't get 8 spacers of various thickness like the picture).