Dyneema and Spectra are brands of lightweight high-strength oriented-strand gels spun through a spinneret. They have yield strengths as high as 2.4 GPa (2.4 kN/mm2 or 350,000 psi) and density as low as 0.97 g/cm3 (for Dyneema SK75). High-strength steels have comparable yield strengths, and low-carbon steels have yield strengths much lower (around 0.5 GPa). Since steel has a specific gravity of roughly 7.8, these materials have a strength-to-weight ratios eight times that of high-strength steels. Strength-to-weight ratios for Dyneema are about 40% higher than for aramid. Dyneema was invented by Albert Pennings in 1963 but made commercially available by DSM in 1990.