2 inches :

you can feed it 2 or 3 times a week with also other things than crickets (It is important to give miscellaneous preys for its health).

Best foods are : crickets, locusts, roaches, earthworms, nightcrawlers and mices.

Add some "calcium powde"r on 2 insects per week and "calcium powder + vit D3" on 2 insects per month for example.