If steps is short for step-ins then the translation would be "culotte." However, with the addition of silicon straps it looks like they are trying to refer to a garter, too. But as you can clearly see from my first & third references, the garter belt was separate from the step-ins.

Wikipedia - Undergarment
Women's bloomers became much shorter and stockings covered the legs instead. The shorter bloomers became looser and less supportive as the boyish flapper look came into fashion. By the end of the decade, they came to be known as step-ins, very much like modern panties but with wider legs, worn for the increased flexibility they afforded.
As dancing became a favorite pastime of young flappers, the garter belt was invented to keep stockings from falling. Nevertheless, the increased sexuality of the flapper also made underwear sexier than ever before. It was the flappers who ushered in the era of lingerie.
http://en.wikipedia.org/wiki/Underpants

2 culotte – briefs 2; panties 1; step-ins
Vocabulaire de l’habillement de Dupré et de Hudon (Cahiers d’Office québécois de la langue française)

The time is the 1930s. Buddy Sandifer, dressed in his natty white flannels, baby-blue shirt, striped tie, tan-and-white shoes, and coconut-straw hat with polka-dot band, is falling into one of his moods. Owner of a used-car lot and father of a fifteen-year-old son with a penchant for sex manuals, Buddy has decided to murder his wife and marry his mistress, Laverne, a robust blonde who cooks his favorite meal of fried pork chops, fried potatoes, and fried apples while wearing a short pink apron over **black-lace step-ins and brassiere, long-gartered silk stockings,** and platform shoes. The only problem is how to arrange the crime.
http://www.franklin.com/estore/dictionary/BBSS0743287606DLDA...

--------------------------------------------------
Note added at 46 mins (2007-05-28 14:20:42 GMT)
--------------------------------------------------

I did find a step-in girdle/garter belt.

There is also the ever-popular step-in girdle which also caters for the full figure.
EK239 Step-in GirdleSize 10-20. Classic step-in girdle with satin front panel and three suspenders (garter straps) per leg for good stocking support.
http://www.glamourcorsets.com/cat/index.cgi/shopfront/view_b...

ceinture-jarretellles ; ceinture porte-jarretelles ; porte-jarretelles - garterb belt
Vocabulaire de l’habillement de Dupré et de Hudon (Cahiers d’Office québécois de la langue française)

--------------------------------------------------
Note added at 1 hr (2007-05-28 14:42:02 GMT)
--------------------------------------------------

It appears that step-ins started out as panties and then over time the phrase has also been used for a "gaine-culotte"

The new, lively dances of the Jazz Age required women to be able to move freely. Underwear called “step-ins” replaced corsets and pantaloons and allowed women to move more freely. Women wound their chests with strips of cloth to flatten it. They wore stockings made of rayon – artificial silk – which they wore rolled over a garter belt.
http://keller.clarke.edu/~english/spring04/am1.htm

In the 1920s, women, determined to liberate themselves, traded bloomers for stockings, and eventually wore step-ins, much like the modern panty but with a wider leg for increased flexibility. And, as dance became popular, the sexy garter belt kept the stockings up. But it was the flapper whose blatant sexuality led to the risqué developments known as modern lingerie.
http://www.nobhillgazette.com/lingerie.html

A flapper was supposed to be a young woman, not yet mature in herself, but with a rather brazen attitude towards life. These new teenaged women drank, smoke, and drove cars. F. Scott Fitzgerald said a good flapper would be “lovely, expensive, and about nineteen.” They were often criticized for their lack of clothing – women of earlier times wore layers upon layers of skirts that went down to their ankles, while flappers were suddenly wearing short, open dresses with **a new scandalous pair of “step-ins” as their only form of underwear.** They refused to wear garter belts to hold up their stockings, and instead rolled these down under their skirts. Flappers also openly wore make-up, something that had been restricted to prostitutes in the past. It was as if girls were smashing the old conceptions of womanhood to the ground, flaunting both their newfound freedom as equal to men and reveling in their absolute womanhood.
http://www.georgetown.edu/faculty/sd224/Classes/ModernAmeric...

'Step-in' seems to be an expression like 'roll-on' which never achieved the same popularity. It referred to the standard girdle or pantie-girdle that could be donned without lacing, zips or hooks. It is mentioned in Tom Sharpe's humorously anarchic book 'Indecent Exposure'. The girdle in question, however, has been borrowed by a man from his wife, which moves us towards the topic of 'the Other Side of Corsetry' . In Mr. Sharpe's book, the Major's wife's step-ins are also referred to as corsets and as a girdle in successive paragraphs.
http://www.corsetiere.net/Spirella/problems.htm

gaine-culotte – pantie-girdle; pull-on girdle; step-in girdle
Gaine ayant la forme d’une culotte avec ou sans jambes, le plus souvent munie de jarretelle amovibles.
Vocabulaire de l’habillement de Dupré et de Hudon (Cahiers d’Office québécois de la langue française)

--------------------------------------------------
Note added at 1 day49 mins (2007-05-29 14:24:10 GMT) Post-grading
--------------------------------------------------

step-in : an article of step-in clothing; as a: a shoe resembling but usu. having a higher vamp than a pump and concealed elastic to adjust the fit b “ a woman’s short panties – usu. used in pl. (Webster’s)