A high potency active B12 supplement containing 500µg of methylcobalamin and 500µg adenosylcobalamin, which are both active forms of this important vitamin.

Sublingual means beneath the tongue and these tablets will dissolve in the mouth allowing oral absorption.
Methylcobalamin is the active form used in the methylation cycle. Methylation reactions occur in every cell in the body – there are more than a billion per second.
Adenosylcobalamin is the active form that is used in the mitochondria (which are the energy power houses of cells).
Vegan and vegetarian diets can be low in B12.
Other people at risk of low B12 include those with digestive conditions that lead to malabsorption; low stomach acid (e.g. due to long-term antacid medication, proton pump inhibitors, H2 blockers, ageing or zinc deficiency); surgery where nitrous oxide has been used as an anaesthetic; and other prescription medications which impair B12 absorption (e.g. metformin, colchicine, neomycin and others).

Vitamin B12 contributes to normal:

energy-yielding metabolism
functioning of the nervous system
homocysteine metabolism
psychological function
red blood cell formation
immune system function

Vitamin B12 contributes to the reduction of tiredness and fatigue

Vitamin B12 has a role in the process of cell division.