The original O-Ratchet Pass Thru ratchet and sockets manufactured in the USA. Discover the convenience of pass-thru sockets that functionally replace one deep and one standard socket, and access restricted fasteners with the low-profile ratchet and socket combinations. This set includes the following metric socket sizes: 10mm, 11mm, 12mm, 13mm, 15mm, 16mm, 17mm, 19mm, 21mm. This set includes the following SAE/inch/english socket sizes: 3/8, 7/16″, 1/2″, 9/16″, 5/8″, 11/16″, 3/4″, 13/16. The set also features an adapter socket turning the ratchet into a 3/8 traditional ratchet. There is also a rubber/polymer insert that can be placed in the larger sockets to convert them for use on sparkplugs or other similar items. I received this set as a gift in the mid 1990s. I do not believe I ever used them. I forgot I had them for many years. All of the components are very high quality heavy construction. The 13mm socket is stamped upside down from all of the others. The 11mm socket is stamped in a completely different smaller script. I suspect it was from an original run rather than later production runs like the other sockets. Detail photos of both are shown. The photos show the socket adapter along with a deep well socket and 3 extension. The extension and deep well are not included. They are only shown to display how the conversion adapter functions.