Identify the date of conception and the calendar marks the approximate birthing date and other events. 21.5cm x 21.5cm (8-1/2” x 8-1/2”) with a hole punched in the top corner so it can be hung anywhere. Printing is blue to allow for easy ready of the wheel. Printing is water resistant. Plastic material is durable in harsh conditions. Inquires for customized Gestation Calendars are welcome.