Best cot mattress sizes: 

There is many sizes for your babies. You can check bellow.

Best cot mattress size for baby australia.
131*75*10 cm: Fits older boori cots, Tosman Eco, Cheeky Bub. Bebe care cots.
130*69*10 cm: Standard cot mattress including cariboo, some grotime
132* 70* 10 cmm: fits IKEA and Boori Urbane cot's.

Get your baby one of the most comfy cot mattresses available. For your child, Milari Organics offers reasonably priced organic cot mattresses. It is constructed from pure latex, coconut coir, certified organic cotton, and 100% Australian wool. It is non-toxic and entirely harmless. With its two-in-one design, babies can sleep in a solid, ventilated zone, while toddlers can rest on

a side cushioned with latex. Natural rubber latex supports improved breathability for a healthier start to life and adapts to the natural posture of the newborn. Convenience and comfort are offered by the organic bamboo outer cover's exceptional suppleness. It zips off for cleaning and washing, serving as both a mattress protection and topper in one.