Our Hasler WJ20 Ink Cartridges delivers quick-drying, USPS approved ink, compatible with your compact WJ20 mail-processing machine. Because the WJ20 is the perfect machine for home-based operations and small businesses, its typical workload is 20 or so letters per week. At that rate, our ink jet cartridge, which yields about 2,500 impressions (without ads), may last as long as a year. While this is a good thing, it also makes it easy to forget to stock up on supplies. Be sure to order your WJ20 Ink Cartridges today.