It is also of critical importance to consider how the joint is clamped, as this will influence the maximum and minimum gap. It is essential that an appropriate thickness of gap filler is selected so that the material is always under an appropriate level of compression. As a general rule of thumb, a gap filler should always be used under a compression of 20 – 45%. To ensure a constant and even pressure in high power dissipation applications, spring clips or fasteners are preferred.