This review could be 5 stars if I could locate the button on Mac Firefox/Mozilla. Locating the button is not straight forward however eventually I could do it on the personal PC. Then I spent >1 hr to search on Mac Firefox and on internet to find the button on the MAC , but eventually I gave up. Without a visible button to click the extension/add-on is unusable. Where I could use it (PC) it appeared to be fabulous. Very upsetting