Brand name for ready-to-wear
made of Dacron polyester
blend fabric with a distinctive elastic waistband
Male anatomy has the drawback of having, like prepubertal children of both sexes, little definition at the waist. This means that anything resembling slacks must have a fairly tight cinch to keep them from slipping, such as a belt -- the underwear-revealing fashion of today is based on the fact that belts are disallowed in prison. However, through a miracle of engineering, Sansabelts stay in place. This is because the Sansabelt waistband features not one but three bands of elastic webbing, forming a girdle-like zone -- allowing free movement with or without the use of a belt! (The enthusiasm of early 60's advertisements is infectious..)
Sansabelts have been around since 1959, about the time that Playboy magazine was beginning to make a stir. As such, they were heavily advertised as being the modern choice for menswear, since they resisted wrinkles (saving ironing), were proportioned for men of action, unlike the fusty "Ivy League" styles, and had a streamlined look that was the perfect counterbalance to Nehru jackets. Now a rather fusty company itself, Sansabelts are still to be found on late-middle-aged men who pride themselves on being "swingers".
Twas ever thus...