Editing Pencil (section)

====Mechanical====
[[File:Mechanical pencil lead spilling out 051907.jpg|thumb|right|Lead for mechanical pencils]] [[File:Biegsame Bleistifte (fcm).jpg|thumb|Flexible pencils]]
[[Mechanical pencil]]s use mechanical methods to push lead through a hole at the end. These can be divided into two groups: with propelling pencils an internal mechanism is employed to push the lead out from an internal compartment, while clutch pencils merely hold the lead in place (the lead is extended by releasing it and allowing some external force, usually gravity, to pull it out of the body). The erasers (sometimes replaced by a sharpener on pencils with larger lead sizes) are also removable (and thus replaceable), and usually cover a place to store replacement leads. Mechanical pencils are popular for their longevity and the fact that they may never need sharpening. Lead types are based on grade and size; with standard sizes being {{Convert|2.00|mm|abbr=on}}, {{Convert|1.40|mm|abbr=on}}, {{Convert|1.00|mm|abbr=on}}, {{Convert|0.70|mm|abbr=on}}, {{Convert|0.50|mm|abbr=on}}, {{Convert|0.35|mm|abbr=on}}, {{Convert|0.25|mm|abbr=on}}, {{Convert|0.18|mm|abbr=on}}, and {{Convert|0.13|mm|abbr=on}} ([http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=16778 ISO 9175-1])—the {{Convert|0.90|mm|abbr=on}} size is available, but is not considered a standard ISO size.{{Citation needed|date=October 2016}}