A 'Trapped' bolt?

[PedroOhare]

What would you call a bolt that is ‘trapped’ so that the nut would slide up and down while the head stayed fixed in place. I am envisaging something like a bolt with a narrow section under the head which would hold a collar that is fixed to the item within which the bolt is placed.

They are used in vises all the time but I am looking for something much smaller.

Thanks

Pedro

[ncosman]

I believe you are describing a "captured" bolt.