Once the adapter is in place the lenses with their mounts are located by twisting the thumb-screw on the adapter unit to secure in position. Also interesting to note broad-arrow markings on some of the mounts indicating previous use by the military. All-in-all a nice easy-to-use system for those who prefer objective lenses on quick-release mounts. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "arcboutant" and is located in this country: GB.This item can be shipped to United Kingdom, Antigua and Barbuda, Austria, Belgium, Bulgaria, Republic of Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Australia, United States, Bahrain, Canada, Brazil, Japan, New Zealand, Israel, Norway, Indonesia, Malaysia, Mexico, Singapore, South Korea, Switzerland, Taiwan, Thailand, Bangladesh, Belize, Bermuda, Bolivia, Barbados, Brunei Darussalam, Cayman Islands, Dominica, Ecuador, Egypt, Guernsey, Gibraltar, Guadeloupe, Grenada, French Guiana, Iceland, Jersey, Jordan, Cambodia, Saint Kitts-Nevis, Saint Lucia, Liechtenstein, Sri Lanka, Macau, Monaco, Maldives, Montserrat, Martinique, Nicaragua, Oman, Pakistan, Peru, Paraguay, Reunion, Turks and Caicos Islands, Aruba, Saudi Arabia, South Africa, United Arab Emirates, Chile, Bahamas, Colombia, Costa Rica, Dominican Republic, Guatemala, Honduras, Jamaica, Kuwait, Panama, Philippines, Qatar, El Salvador, Trinidad and Tobago, Vietnam.