What appropriate feeder size should I feed my hatchling?

I have a supply of crickets but adult sizes. What appropriate size should I feed my leo? Half the size of the head, size of the whole head or what? Its 3 inches. Can I prekill the crix and feed it to my leo? Thanks.

You should feed no insects wider than the space between the gecko's eyes, and insects with exoskeletons like crickets should also be about three-fourths the length of the gecko's head. You should not feed adult crickets to a hatchling, even pre-killed, because the exoskeleton will be difficult for the hatchling to swallow and digest properly.