I believe these are glasses from Zoff's lightweight and durable series. The prescription is likely -3.75 in both eyes, or slightly weaker. Please visit a Zoff store for lens prescription changes and size adjustments. [Brand] Zoff [Model Number] ZH11011A [Size] 51◻︎17-140 *These will be wrapped in bubble wrap and shipped via post. Please understand that these are used items before purchasing.