Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
As early as 1931 McKenzie designed an artificial vagina for the collection of boar semen. For convenience, it will be referred to as the Type A vagina. It consists of a soft rubber tube, 16 in. long, one end of which is fitted over the mouth of a test tube. The other end is fitted over a 15/8 inch key-ring. An ordinary clamp completes the outfit. The rubber is band tubing, 13/16 in. inside diameter and 1 Y2 in. outside diameter.
Herrick, John B.
"Artificial Insemination Of Swine,"
Iowa State University Veterinarian: Vol. 12
, Article 4.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol12/iss2/4