Internal Nipple Id

woolwich

I have a slight wobble in a deep (85m) section carbon time trial rim. I have built and trued a few dozen sets of wheels so am confident I can true it myself but need some help with the nipple identification.
I pulled the tub off and expected to see either a standardish nipple head or a hex type. Instead I can see what looks like a cylindrical nipple with two flats. A bit of googling would suggest I need to pick up a long reach driver with a 3.2mm square end.
Can anyone confirm this is correct before I buy?

Thanks

Monty Dog

I've used Sapim hex nipples inverted for internal use no problems - you can then use a regular driver. Importantly, don't use a regular nipple with a slotted head inverted otherwise it will chew the carbon rim bed unless you fit a brass washer.

woolwich

Thanks Monty.
I could well be looking at a sapim hex the wrong way round, hard to tell down the hole, they look to have just two flats but this might just be some marks from manufacturing. I will try a long reach square head driver on it.