Cqma's waterproof seal is cleverly designed so that when under pressure from the outer bevel of the female head, an o ring rests in the groove of the male head's outer conductor creating an excellent seal and anti-shock effect.
In the cqma design, the spring lock in the male head is made of stainless steel (1/10 the price of beryllium copper) and consists of a ring-like locking sheet with inner and outer teeth.
In the interest of improved reliability, the effective contact length of the original sma conductor, 2.3mm, ought to be maintained, and is matched in the cqma design.