Apple Mac OS X Mountain Lion - 10.8.5 - Instant Download Link (4.2GB File Size)100% reliable. When you select this item and make payment, the download link will be sent in an email to your registered PayPal payment email address within 30 minutes of payment. Also can provide advice on download issues. However this link is simple. Simply Hit the Link and Download the operating system follow the onscreen prompts. Good Luck and please leave positive feedback if happy with this transaction: