The phrase "a special grade of" is correct and usable in written English.
It can be used when referring to a specific category or quality of something that is distinguished from others.
Example: "This wine is known for its unique flavor, which comes from a special grade of grapes grown in the region."
Alternatives: "a unique type of" or "a distinct category of".
The finished product can be wrapped in plastic instead of being covered with a special grade of low-iron glass on a hard backing.
The links are of a special grade of steel that deforms more easily than other grades, and they are placed at specific points along the length of the tower, which affects how the shafts will move in a quake.
Hydraulic transmissions require a special grade of light hydraulic fluid, and manually shifted transmissions use a heavier gear oil similar to that for rear axles to resist heavy loads on the gear teeth.
Chinese white is a special grade of zinc white used in artists' pigments.
Legally, midshipmen are a special grade of officer that ranks between warrant officer (W-1) and the lowest grade of chief warrant officer (W-2).
These lice are treated using a special grade of petroleum jelly that is safe to apply on the eyes.
Continuous pre-stabilization of a special grade PAN fiber has been carried out in four different temperatures under three distinct imposed stresses, namely Free Shrinkage, Zero Shrinkage and Under Stress treatments.
The town is administered by a special grade municipality that covers an area of 16.33 sqkm and had a population of 144,278 in 2011.
Since 1983, Thanjavur has been a special grade municipality.
This work was supported by the Major Project of China's "Eleventh Five-Years Plan" for Science and Technologies Development (2009ZX10004-902 and 2008ZX10001-004) and the special grade of the financial support from China Postdoctoral Science Foundation (200902022).
Extent of coronary sclerosis was determined by a special grading system in accordance with an evaluation system of the American Heart Association [ 17].
