I need a tool

[allen.traveltech]

This is a metal rollup door. There is no branding on the door anywhere (I looked so dont tell me to go look). There is usually a device like this with round holes for adjusting the tention on the spring but this one has flat ends. I tried a crowbar but that slips quite easily. This is an open job and time sensative. If someone here has seen or played with this device please email me directly - allen.traveltech@yahoo.com.

What tool is used for this?

Thanks
Allen