An unstable compound of strontium molecules encased in the crystal structure of water. When fed to a Control Tower's force field generator, these clathrates bond with the molecules already in place in the field to create a nigh-invulnerable barrier of energy. A necessary ingredient for Control Towers to go into reinforced mode. May be obtained by reprocessing the following ice ores: 1.0 security status solar system or lower: Blue Ice Clear Icicle Glacial Mass White Glaze 0.3 security status solar system or lower: Glare Crust 0.1 security status solar system or lower: Dark Glitter 0.0 security status solar system or lower: Enriched Clear Icicle Gelidus Krystallos Pristine White Glaze Smooth Glacial Mass Thick Blue Ice