Male-Female stacking spacers come in round and hexagonal profiles and are precision manufactured for demanding PC/104 and PC/104-plus embedded applications. The spacers are available in nylon and aluminum, and are machined for a perfect fit. With the stacking spacers, circuit boards are spaced exactly 0.6 inches apart to build structurally secure module stacks. The standalone stacks can be used like ultra-compact bus boards, but without the need for backplanes or bird cages. This way, system designers can easily assemble application-specific module stacks for their products.