Chime blocks come in many different designs. The chime block sets have been categorized by the number of rods.
When choosing a chime block there are a number of aspects to consider:
Repairing a chime block can be difficult. If a chime block has screw-in rods a replacement rod can be inserted; however, the chime block must be tuned by a professional. If the chime block has press-in rods the block cannot be repaired.
Chime block rod lengths do not have to be exact to what you are replacing. The clock case and mounting requirements will determine the needed size of the rods and blocks.