Coenzyme Q10 (CoQ10) is a natural antioxidant made by the body. It exists in two forms: ubiquinol, the active form of CoQ10, and ubiquinone, the oxidized form of the antioxidant, which can be partially converted to ubiquinol. Studies have shown that ubiquinol possesses superior bioavailability to ubiquinone, meaning it is much more efficiently absorbed into the body and blood stream. 
Ubiquinol plays an essential role in the body’s ability to produce energy, in addition to having powerful antioxidant potential, protecting the body’s cells from damage caused by oxidative stress and free radials. As a result, ubiquinol is known to help with various age-related diseases. 
Foods such as fish, poultry, and meats are good dietary sources of the antioxidant. However, as we age, our ability to absorb ubiquinol as well as convert it from ubiquinone becomes increasingly difficult. This is why including supplemental ubiquinol is recommended.  
Individuals wanting to help support cardiovascular health, or those over the age of 40 wanting increased energy and general wellness will benefit from Natural Factors Ubiquinol QH Active CoQ10. Studies dosing from 300 mg to 1200 mg per day for 16 months of ubiquinol have not reported any concerns of toxicity. However, consulting a health care practitioner prior to use is always recommended. 
References: 
Evans M, Baisley J, Barss S, Guthrie N. A randomized, double-blind trial on the bioavailability of two CoQ10 formulations”, Journal of Functional Foods 1 (2009): 65-73
Retrieved from; http://www.integratedhealth.com/downloads/CoQ10Study.pdf
Langsjoen PH, Folkers K., et al., “Treatment of essential hypertension with coenzyme
Q10, in: Eighth International Symposium on Biomedical and Clinical Aspects of
Coenzyme Q10 (1994), The Molecular Aspects of Medicine, vol 15, S287-S294; 1994.
Langsjoen PH., Langsjoen AM. “Supplemental ubiquinol in patients with advanced
congestive heart failure”, BioFactors 32(1-4):119-12, 2008.
Shoko J., et al., “The effect of Reduced Form of Coenzyme Q10 (Ubiquinol, Kaneka QHTM) on QOL Improvement in the Elderly”, J Clin Therap Med 24, (2008): 233-238 (English translation)