Lt Colonel Jacob Schick invented his first razor in 1921 which was inspired by a repeating rifle. It went into production in 1926 at which time the "Magazine Repeating Razor Company" was founded. He sold the company in 1927 to persue other interests. Worldwide they are second in sales to Gillette.

Fast forward to the 1960's at which time it was owned by Patrick Frawley and when they started producing adjustable razors. It was also around this period (1970) that the company was sold to Warner-Lambert Company.

Although the Krona is far more collectable than the injectors - it is the injectors that Schick are most well known by so I'll start with them.
All the injectors are Type M's and there appear to be at least seven versions dating from about 1965 to 1980. One of the seven is considered a prototype.
There seems to be quite a bit of interchanging between numbers 2 and 3 below with adverts as early as 1965 and as late as 1973 showing SCHICK ADJUSTABLE on the insert.
    1 - The Prototype or limited Canadian version.
    2 - Black handle with insert that says "Schick Adjustable". (CLICK HERE)
    3 - Black handle with insert that says "Schick Dial". (CLICK HERE)
    4 - Grey Handle with insert that says "Adjustable by Schick" without the Protector function. (CLICK HERE)
    5 - Grey Handle with insert that says "Adjustable by Schick" with the Protector function. (CLICK HERE)
    6 - Grey Handle without an insert with the Protector function. (CLICK HERE)
    7 - Grey Handle without an insert with the Protector function and the word Schick on the head. (CLICK HERE)

The patent for the Adjustable injectors was granted to L.K. Kuhnl assignor to Eversharp Inc on August, 31 1965 and the number is US3203093 (Click to see) or a more detailed patent can be found HERE.

They also made an adjustable Cartridge razor and the Techmatic Band razor.

Schick Adjustable	Schick Dial	Adjustable by Schick ®
Schick then introduced the "Protector" lever.
Adjustable by Schick ® with Protector	Grey Handle No Insert with Protector	Grey Handle No Insert with Protector / Shick Logo

We will move onto the Krona Adjustable HERE
Its the only DE Adjustable that was manufactured by Schick but it never went into production.

Krona Adjustable