Female inverted phillips head wrench ???

[Catfish]

It's most likely a common wrench  , speaks Chinese to me....female inverted Phillips head  ...short as you can see...cast iron...never used...like the other small square wrench. No manufacture marks...came in the same box with the Charles miller socket set. thanks for any insight...

[Papaw]

For turning a wing nut?

[johnsironsanctuary]

It looks like a tank wrench. Could it be for some proprietary valve ? WAG

[Catfish]

Well starring at  it more closely.... could it possibly be a square nut socket wrench ? with it being made from this Miller who made custom wrenches . Being a wrench for straight in ( like through a hole or shield ) tight nit spots were you can't get the other ( squared wrench in picture ) in from the side ?

[Billman49]

Looks like a security wrench for some sort of spigot (tap/faucet - whatever term you use in the USA...)