ID?

[wantacoe]

Anyone know what this is. I have a few of them in different sizes. There is supposed to be a o ring in the groove I marked in red.

 

[kbuhagiar]

Nutsert tool mandrel - circled in the picture below.

Nutsert Conversion Kit 1/4-20 | Aircraft Spruce ®

Nutsert Conversion Kit 1/4-20 AA-112 HI-Torque Nutsert Conversions, using this hi-torque tool, ideal for field and maintenance applications.

www.aircraftspruce.com