these are called "atom photovoltaic glass" mousepads on aliexpress or in my country, from shopee/lazada/tiktok shop, they have a non-standard texture (if you look closely there's miniscule tiny indents) vs all the other glass pads you see in the market which are just flat surfaces i think and thus require you to wear an arm sleeve, i dont need one for this though, sweat and grime actually makes the glass easier to the skin lol, if i were to clean the mousepad fully clean with alcohol, my arms would stick way worse compared to getting sweat and grease in, anyways the mousepad costed me around $18 at the time, the skates i have are xraypad obsidian clones, the red ones, also bought from aliexpress or the other sites for like $0.5 a pack