Mice Food Hopper

Sorry for the extremely noob question but I honestly have no idea how food hoppers work..
The mice are supposed to nibble away at the blocks slowly through the holes right? Not be able to pull one out when they need to eat. Does this mean that the food has to have little bits and corners sticking out of the holes or can they reach in?

But more importantly, Whats the best size hardware cloth or wire mesh to use for food hoppers for mice? I've read that 1/4 inch holes is best since young mice can squeeze through 1/2 inch ones but I honestly dont see how its possible that the mice can eat anything through those tiny holes that only their noses fit through.

Thanks!!

oh and one more thing. my mice started biting through the hardware cloth trying to get access to the food. at this rate theres going to be a hole in it and foods gonna start spilling out too. and the mice can get into the food bin. you guys get the same problem? im sure almost all of you breeding mice do it in racks with the food hopper being a mesh on the top with food above it. what do you guys do?

I made my hoppers out of 1/2" square hardware cloth/wire. This is too tough for them to chew through. Mine are mounted to the lids of my breeding tubs and hang down inside the tub, stopping about 2" from the tub bottom. Since I use sterilite tubs, I cut roughly half of the lid out and replace it with 1/4" square wire that I zip tie in place. Yes I do occasionally have hoppers squeeze through the hopper mesh, but not as many as you would think.

I solved that problem by adding a hatch cover to the top of the hopper. Basically, once the hopper is constructed and mounted to the wire lid, I cut a piece of aluminum window screen about 1/2" larger than the opening all the way around. I use two tiny zip ties that are not pulled completely tight as hinges in the back, and a simple bread tie to hold the front down. It is super easy to open the hatch and add food, and tiny little hoppers aren't strong enough to damage the screen lid.

Gale