Pentel of America, Ltd. BK91D ballpoint pen, medium point, green ink, clear barrel, dozen

Everyday writing pen

The Pentel BK91D is a medium-point ballpoint pen with green ink and a clear barrel. It is sold as a pack of twelve for offices, schools or home desks that need a reliable supply of the same colour. The refillable design means the barrel can be kept and reused when the ink runs out.

Ballpoint ink behaviour

The oil-based ink flows consistently on standard copier paper and forms a permanent line once dry. It is not suited to glossy, coated or water-resistant surfaces where the ink may smear or fail to adhere. Broad strokes or fast writing can leave occasional gaps because the ball delivers a fixed volume of ink per rotation.

Comfort grip and refill system

A rubber Comfort Zone section wraps the barrel where the fingers rest, reducing pressure during long sessions. The clear barrel lets the user see the remaining ink level at a glance. Refills are inserted from the front after unscrewing the tip, so the pen stays in service without replacing the whole body. Buyers who want a capped rollerball or a finer needle point will need a different model.