Summit TwinLix Salt Block. Common salt (sodium chloride) is an essential constituent of an animals diet. Summit TwinLix Salt Block provides essential trace minerals (Cu, Zn, Co, I, Se) with salt as a carrier. The blocks can be used all year round with all stock classes except Texel sheep (as copper supplements can be toxic to Texel’s). TwinLix are sold in a convenient carry pack of 2 x 2.5kg blocks.