Bottom views of CD 1030 variants

Top row (left to right): [010] Knurled nut, [020] lag screw, [030] machine bolt

Bottom row (left to right): [040] slotted base (round hole), [050] slotted base (square hole)

All in the top row are Ice Blue, and those on the bottom row are clear. Also look at the [id=126189907; front views] of these.