Brass
Includes clear window (plastic)
10/Pack

This size will fit in a 5/32" (4mm) hole.

This size is available with or without the bolt holes around the flange, you can choose the version you want from the dropdown menu. With will provide the porthole in the image. Without is the same thing just without the miniature holes around the flange. $5.00 discount for the version without the holes.

Dimensions:
R= 1/4" (6mm)
r= 1/16" (2.4mm)
d= .8mm