Dumbbell, barbell, and kettlebell

A simple dumbbell, comprising a dumbbell rod, an adjustment component, and a dumbbell piece,

• two semicircular telescopic rods are provided in the dumbbell rod, a square groove is respectively provided in a middle of each of the two semicircular telescopic rods;
• a square rod is provided on the two square grooves, a fix hole is respectively provided at two ends of the square rod, wherein the two ends of the square rod extend in opposite directions;
• the two semicircular telescopic rods are each provided with a limit tooth, respectively;
• the adjustment component comprises an adjustment arm and a locking component, a middle of the adjustment arm is provided with a connection hole, a connection component connecting to an installation seat is provided in the connection hole, an adjustment area is provided below the adjustment arm, the adjustment area cooperates with the locking component to adjust the two semicircular telescopic rods that pass through the adjustment component;
• the dumbbell piece is provided on an outer side of the adjustment component, the dumbbell piece is provided with a connection groove to connect to a respective semicircular telescopic rod of the two semicircular telescopic rods;
• wherein the locking component comprises a locking piece with a first bend, a semicircular hole, a convex tooth, a first limit groove, a support column, a second bend, two first positioning pieces, a fixing piece, a spring, and a second positioning piece;
• wherein the connection component comprises a connection buckle and a connection shaft;
• wherein each of the two first positioning pieces comprises a second limit groove and a blocking piece;
• wherein the fixing piece is U-shaped, with a fix groove at a bottom thereof;
• wherein the second positioning piece comprises a circular hole and is connected to the fix hole at one end of the square rod.