Slide Fastener Chain and Slide Fastener

A side fastener chain, comprising:

• a pair of fastener tapes;
• and
• a plurality of elements fixed on each of opposing edge portions of the fastener tapes at a predetermined pitch;
• wherein the elements comprise a base portions fixed on the respective fastener tape and a head portion protruding from the base portion and configured to be engaged with the opposing elements,
• wherein a ratio (Rt) of the sum dimension of a first partial thickness, which is measured from an upper surface of each element to an upper surfaces-side apex of the respective edge portion, and a second partial thickness, which is measured from a lower surface of the element to a lower surface-side apex of the edge portion, to a thickness of the element satisfies the following equation (6), and
• wherein a ratio of the thickness of the element to the entire length of the element satisfies the following equation (7).
• 40%≦Rt (6)
• 0<Rtl<60% (7)