Strength chains — Miniature sequence 7:
Product: seven X seven X R 18, 28, 38. (B)
Note 1: Hi=Iner top, Bi=Iner width, H=Outer top, Ba=Outer width
Observe 2: The opening way B suggests non opening type.
The opening way F indicates the convenient sort.
The opening way BF implies the enclosed variety.
The opening way W indicates exterior opening type.
The opening way S indicated double sides opening variety.
The opening way N indicated Inside opening sort.