Pentel AIN Stein Mechanical Pencil Lead Refills 0.3/0.5 /0.7/0.9-H/HB/B/2B/3B/4B | eBay
Amazon.com: Pentel Ain Stein Mechanical Pencil Lead, 0.5mm B,2B,3B,4B (40 Leads) 1 Each + Original 5 Colors Sticky Notes
Amazon.com : Pentel Lead Refills 0.5mm 4B, Black, 12 Leads per Tube (C505-4B) Pack of 3 : Office Products
Uni Smudge-Proof Lead - 0.5 mm - 4B | JetPens
Amazon.com : June Gold 640 Pieces, 0.5 mm 4B Lead Refills, 160 Pieces Per Tube, Fine Thickness, Break Resistant Lead/Graphite (Pack of 4 Dispensers) : Office Products