Tenon measures 24.55 milli-metres on my digital vernier gauge. B This may need adjustment to fit your horn perfectly.No serial number so precise age / vintage unknown but I estimate mid to late period / late 60's to early 70's. The item "Selmer Mark 6 Alto Saxophone Crook Neck M6 MKV1 VI six sax" is in sale since Sunday, November 1, 2020. This item is in the category "Musical Instruments\Wind & Woodwind\Band & Orchestral\Saxophones". The seller is "alienduffer" and is located in Frome. This item can be shipped to United Kingdom, United States, Japan, Canada, Ireland, Australia, Germany, France, Greece, Italy, Spain, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech republic, Denmark, Estonia, Finland, Hungary, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Sweden, Bahrain, New Zealand, China, Israel, Hong Kong, Norway, Indonesia, Malaysia, Mexico, Singapore, South Korea, Switzerland, Taiwan, Thailand, Bangladesh, Bermuda, Bolivia, Barbados, Brunei darussalam, Egypt, Guernsey, Gibraltar, Guadeloupe, French guiana, Iceland, Jersey, Jordan, Cambodia, Liechtenstein, Sri lanka, Macao, Monaco, Maldives, Martinique, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Saudi arabia, South africa, United arab emirates, Ukraine, Chile, Bahamas, Colombia, Costa rica, Guatemala, Honduras, Jamaica, Kuwait, Panama, Qatar, Trinidad and tobago, Uruguay.