HP 31 ink bottle works with: HP Smart Tank Plus 651, HP Smart Tank Plus 551 Easy and spill-free refill system: Replenishing ink is clean and quick with HP HP 31 ink bottle yield (approx.): 8,000 pages What's in the box: 1 New HP 31 ink bottle Black and composite color average per bottle (cyan/magenta/yellow) results based on HP methodology from the simulation of continuous printing of ISO/IEC 24712 test pages. Not based on ISO/IEC 24711 test process. An additional black ink bottle is required to print 8,000 color test pages. Actual yield varies based on content of printed pages and other factors. Some ink from included bottles is used to start up the printer. For more information about fill and yield, see hp.com/go/learnaboutsupplies.