0. 3 mm diameter is considered to be relatively thin. This size of lead might not be suitable for writing or sketching, but using it you’ll be able to draw with very minute detail. 0. 5 mm thick lead is used to be one of the most common sizes of lead. You might use 0. 5mm lead for writing or drawing. Overall, it’s still a versatile size that might be just right for your writing needs. 0. 7 mm lead is a thicker variety, which makes it suited to sketching and non-detailed work. You may also find this lead useful if you do long-hand drafting. It it also more common nowadays compared to 0. 5mm, as cheaper mechanical pencils became more popular using 0. 7mm. 0. 9 mm lead is an even thicker lead. It can be used with a rather soft lead, and therefore will have less breakage. Good for puzzles on newsprint (crossword, sudoku).
Some specialty leads, like sizes 2 mm and up, require sharpening, unlike most other kinds of mechanical pencil lead. You should follow the directions that come on the packaging of your lead to learn the best process for sharpening. [3] X Research source
Soft lead. The softness of this lead is represented by a number followed by the letter B. The higher the number, the softer the lead. Therefore, 4B lead will be very soft, 3B lead less so, and so on. Medium lead. With medium leads, the letter B represents the softest kind and will write like a No. 1 pencil. HB medium leads write the same as a No. 2 pencil. F medium leads are similar to a No. 2½ pencil. Last but not least, H medium leads will be hardest and correspond to a No. 3 pencil. Hard lead. The hardness rating for hard lead is indicated by a number followed by an H. As the numbers increase, so too will the hardness of your lead. An 2H pencil (corresponding to No. 4) will be softer than a 3H pencil, and so on.
Heavy handed writers may find fine points break easily when writing, while soft leads leave behind thick, clumsy looking lines. If you’re one such person, you may want to stick with medium thickness leads of medium hardness or harder. Light handed writers may have difficulty with harder leads. You may find, if you have a lighter touch, that hard leads force you to press with your pencil harder than is comfortable.
A sleeve will give you a better view of your drawing/writing area, making this feature an asset if you do detail work in pencil. However, you should be careful when pocketing a fixed sleeve pencil; the points of these could easily jab you in the leg. Sliding sleeve pencils are able to retract within the body of your pencil. If you enjoy writing with a sleeved pencil but don’t like getting poked when it’s in your pocket, this option may be right for you. [5] X Research source
When using a less common sized mechanical pencil, you may want to carry replacement lead with you. This way, you won’t have to scrounge for specialty lead if you run out.
Push button lead advances come in a two different types. Some have a button on the side of the pencil, others use a top button that combines with the eraser. In either case, you can advance your lead by pressing the button. Twist-operated lead advances were more common in older models. By twisting the barrel of your mechanical pencil, you’ll cause the lead to advance. Some models may have a continuous lead advance, where the more you twist, the more lead is advanced. A shake advance can be activated by giving your mechanical a firm shake up and down. This motion will cause a small weight on the inside of the pencil to advance the lead.
Some pens come with a triangular shaped grip. This may feel strange to you at first, but some users appreciate the additional contact this kind of grip gives with the pencil.
