A:
The higher the number the thicker the width of the lead. Typically, .7mm is the standard lead, .5mm is a fine point lead. If you're looking for a stronger lead, I suggest either .9mm or .7mm.
You may be interested in item 771469; .9mm Lead. To view, click:
http://www.staples.com/Pentel-Super-Hi-Polymer-Lead-Refills-09mm-HB-45-Leads/product_771469Please note: The mechanical pencil used may only be compatible with a specific size of lead.
Answered on 4/10/2012 by Kayla T. from Staples