Weight-adjustable dumbbell apparatus

A weight-adjustable dumbbell apparatus, comprising:

• a handle and two sets of dumbbell plates, each set of the two sets of dumbbell plates comprising a primary dumbbell plate and a plurality of secondary dumbbell plates, wherein each primary dumbbell plate is fixedly attached to a respective end of the handle;
• and at least two connection assemblies disposed between any two adjacent dumbbell plates of the two sets of dumbbell plates, wherein each of the connection assemblies comprises:
• a protrusion member extending from a first plate of the any two adjacent dumbbell plates;
• a first receiving recess formed in a second plate of the any two adjacent dumbbell plates;
• a locking plate disposed within the first receiving recess;
• and a first engagement recess disposed on the protrusion member;
• wherein the locking plate is configured to engage the first engagement recess upon a relative rotation between the first plate and the second plate of the any two adjacent dumbbell plates to prevent axial separation thereof, and wherein a surface area of the first receiving recess is greater than a surface area of the protrusion member;
• wherein each of the dumbbell plates comprises an outer casing, a mounting plate, and a weight core, wherein the outer casing is provided with an engagement block having a sloped surface, the mounting plate is provided with a corresponding third engagement recess, and wherein an edge of the mounting plate is provided with an auxiliary notch.