The 30-40 mmHg level of compression is a stronger medical grade class II. It’s recommended for leg health symptoms that range from moderate to severe. The 30-40 mmHg level of compression is also recommended when you have a blood clot or a deep vein thrombosis DVT. Patients with lymphedema are also recommended to use the 30-40 mmHg level of compression. When choosing the 30-40 mmHg compression, also be sure to think about what kind of fabric your compression stocking or sock should be. Because the stocking is providing more compression in the 30-40 mmHg strength, it’s a good idea to choose a more durable material. Sheer compression stockings that are 30-40 mmHg may be more prone to snags and holes.