1.125 it does not have a keyway drive slot. Machinery huge extra spare parts. This is not an actual photo but it is pretty much 100% identical to the one in the photo, I have had a few of them in the past that were pretty much all the same so I have used this same photo for each one.
The item "New 10+ Diameter Involute machine SPARE Lathe Parts gear 80 teeth 1-1/8 Hole" is in sale since Tuesday, July 2, 2013. This item is in the category "Business & Industrial\Industrial Automation & Motion Controls\Mechanical Power Transmission\Gears & Gear Racks\Other Industrial Gears".
The seller is "dj-machinery" and is located in Grand Rapids, Michigan. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Sweden, Belgium, France, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Mexico, New Zealand, Switzerland, Norway, Ukraine, Croatia, Chile, Colombia, Costa rica, Dominican republic, Panama, Trinidad and tobago, Guatemala, El salvador, Honduras, Jamaica, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bermuda, Bolivia, Ecuador, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Cayman islands, Liechtenstein, Luxembourg, Monaco, Martinique, Nicaragua, Paraguay, Bahamas, Uruguay.