Magnesium L-Threonate is among the most absorbable forms of Magnesium Pills. It is used to support memory, sleep quality, and to promote overall cognitive function (especially as one ages). Magnesium L-Threonate is patented under the name Magtein and has been clinically studied to raise magnesium levels in the brain and support cognitive function. Double Wood’s Magnesium L-Threonate supplement are Made / Tested in the USA, Non-GMO, Gluten Free. Each bottle contains 100 Capsules and each capsule contains 500mg of Magnesium L-Threonate. Each 4 capsule serving contains 500mg of Magnesium L-Threonate. Consult your physician before use: Known side effects of Magnesium Threonate include drowsiness, dizziness, heartburn, nausea, headaches, anxiety, insomnia, nightmares, skin irritation, redness, and rashes, constipation, nerve pain. Allergen Notice: Contains Rice Flour and may cause skin irritation, redness, or rashes. Do not take if you suffer from anxiety attacks. Do not take if you are on other medications without approval from your physician.