Braeburn5970 Universal Thermostat Guard with Keyed Lock

my thermost is 71/2wx51/2hx21/2d what kind of thermostat do I need to fit it?

Is there an inner lip to block something from being put through the slots?

Can the cover be forced open, I had this problem with a Honeywell box?

Is it well ventilated to prevent temperature fluctuations?