The Dewalt DCF899B is lighter than the Dewalt DCF899HB by around 0.6 lbs despite having the same dimensions. This is mainly due to the different anvils used within these tools. The DCF899B has a detent anvil, which offers a better grip on the workpiece compared to the DCF899HB, which has a hog ring anvil. The latter allows you to switch between workpieces quickly. The detent anvil mechanism is much easier to maintain and repair, as it does not need any specialized tools. However, the hog ring anvil requires the use of hammers and screwdrivers, making for a slightly more complicated maintenance procedure.