This tailpiece attaches to the banjo by means of a single nut & bolt through the angle sticking out at the bottom.
There are 5 studs on the back of the tailpiece for the strings to loop over - these studs no longer have slots cut through them so this tailpiece is really only suitable for loop-ended strings.
The approximate dimensions are-
Top section: 28mm wide x 8mm long
Angle section: 28mm wide at the top narrowing to 8mm wide at the bottom x 20mm deep
Fixing section: protrudes from the angle section by 10mm; 8mm wide with 4mm hole for fixing bolt