Two that come to mind are Pilot Dr. Grip and Pentel Gizmo... Pentel Gizmo used to be my favorite mech. pencil because it had a tip that would automatically retract as you write... so you click less. We used to have a store around here... it basically just sold stationary supplies (unlike Staples which sells a lot more other things) and it was THE place to go to for mech. pencils and pens... I wish I knew of a B&M place to get the oddball lead sizes.