Gearbox drain and filler plug tool?

Hallo All.
As a newbie to 4X4s I have recently bought a 2001 Jimny auto (convertible with hardtop) and will shortly be changing all the fluids.
The drain / fill plugs seem to have a square recess to undo.

Probably a daft question but can anybody tell me if they all the same, what size this is and whether there is a recommended tool to remove them without damaging them.

Thanks in advance
John

10mm x 10mm
I just filed down a big bolt until get a perfect snug fit.

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<img src="i.ebayimg.com/thumbs/images/g/PQ4AAOSwEOpaDqqB/s-l225.jpg" alt="SQUARE OIL DRAIN PLUG SOCKET TOOL 8mm 10mm & 17MM SOCKET SOME RENAULT PEUGEOT"/>
£6.57p

Thanks HUN.
An ingenious solution.
Have been cruising the topics and someone else has suggested this tool .....

Genuine Laser Tools 6065 Drain Plug Key - 8/10mm Square

The sump fill/drain plugs can be VERY tight, i have this in my tool box and it fits three of my cars and my van.

Thanks guys I'll get one of those tools ordered.

Thanks. Yep, I used to have something similar. Unfortunately I was daft enough to lend it to a mechanic thinking he'll give it back later... Never happened. And it was so bloody pricy considering what it is! Hence the bolt replacement.

Remember to undo the top one first