Birth Date Finder Wheel Calculator. Digitally printed high resolution Full Colour & varnish directly on to the .020 White Vinyl Plastic. This makes for a top quality, long lasting wheel. Use our standard template or supply your own customized one. Ideal for Fertility Clinics, Reproductive Centers, Obstetricians & Gynecologists. Can also be used for Gestational calculations in the livestock industry. Top wheel 3.25" dia. & Bottom wheel - 4.25" dia. Separately priced options - back imprint.