I've been researching some magnesium lotions/gels available here in Canada and was wondering about this one (Natural Calm):

"Each 8oz (237ml) bottle of Transdermal Magnesium Chloride Gel is estimated to deliver 60 mg of magnesium per undiluted milliliter.
Ingredients: Each 1ml of seawater contains 225mg of magnesium chloride. Potency equivalent: 60mg
Non-medicinal ingredients: Distilled water, amigel. Contains no fragrance"

Is that a reasonably potency? These items are not cheap, so I want to make sure I choose the right one!

Any thoughts or suggestions on other brands - bearing in mind my location.

Many thanks, Linda