The standard MakerSlide eccentric spacer (left, below) has two new brothers.
Both new members of the family are designed for plastic carriages. They are wider (10 mm instead of 8 mm), have the edges chamfered on both sides, and have longer necks. These features make them friendlier on softer materials, such as 3D-printed MakerSlide carriages. One spacer is the same height as the original (6.35 mm, or 0.25″); the other is a diminutive 2 mm, for those low-profile applications. You’ll probably need a thin spanner for it.