There are two types of threaded rivit, some are a round head just like a rivit and often sold as slotless screws. These are easily availble from EKP etc
The type STW use are more like domed hexagon nuts and bolts where most of the hex has been machined away from the nut leaving just enough to turn it by, the threaded part of the bolt is a reduced thread and you really only notice them up close. I think STW may sell them but I've not seen anyone else doing them.

J
Edited By JasonB on 04/08/2014 21:48:15
Edited By JasonB on 04/08/2014 21:49:24