GUARANTEED TO WORK ACOUSTIC RESEARCH MODEL AR-4X.SERIAL NO.408593.SHIPPING WEIGHT WOULD BE 22 POUNDS.WE ACCEPT CREDIT CARD OR PAYPAL.CHECKS WILL HAVE TO CLEAR BEFORE SHIPPING.THANK YOU FOR LOOKING.I HAVE NOT OPENED CASE.Unfortunately, the three models AR-4, 4x and 4xa are frequently used synonymously when searching for one of these speakers on auction websites. If you wonder what the difference between the AR-4, AR-4x and AR-4xa is, here is a short simple answer: It´s all about t...he tweeter!The AR-4 is the oldest of the three and by now a sought after collectable made in 1964. The AR-4x is its successor and from late 1965 and 1966. The AR-4x has 2 1/2" cone tweeters, whereas the AR-4 has 3 1/2" tweeters. The AR-4x received outstanding reviews and is until today famous for its sound quality. Finally, in 1973, the then AR-4xa speaker had been introduced. The tweeters were switched to the 1 1/4" tweeters used in the AR-6 and AR-7.I AM NOT GOING TO OPEN TO SHOW SPEAKERS, SORRY!IF BOUGHT AND SPEAKER DOES NOT WORK, I WILL GLADLY REFUND ALL MONIES.