Collar Pin

FIG. 1 is a front view of a collar pin of my new design; FIG. 2 is a rear view thereof; FIG. 3 is a left front perspective view thereof; FIG. 4 is a right front perspective view thereof; FIG. S is a top front perspective view thereof; FIG. 6 is a bottom front perspective view thereof; FIG. 7 is a front left perspective view thereof; FIG. 8 is a rear left perspective view thereof; FIG. 9 is an enlarged front view of an end portion of the collar pin shown in FIG. 1 ; FIG. 10 is an enlarged rear view of the end portion of the collar pin shown in FIG. 2 ; and, FIG. 11 is an enlarged front left perspective view of the end portion of the collar pin shown in FIG. 7 . The dot-dash broken lines represent the designation of enlargement views and form no part of the claimed design.