Steel knob for rear roll up window

This steel knob with nail shank is used in two places on early T'. 5/8" long shank.

1. The leather straps for the rear “Roll Up” window curtain hook to the knob. (Straps are part number 7831RL). In this use that are nailed into rear bow. They were original in 1909-1913 but can be used on Model T with any roll up strap.
2. 1909-1910 cars also used them to hold the rear curtain to the rear buggy rail by inserting shank into a pre-drilled hole and then peening over the end. They are then used to fasten to curtain in place when it is in the down position. (The curtains have a metal loop on them that holds the curtain to the knob, part# B-LOOP.)