Why only dumb bells?
A barbell a much better long term investment.
Dumbbells are actually better, barbells make the body asymmetric (dominant hand and leg takes most of the brunt, effectively keeping the less dominant limb weaker - next time focus and try to gauge this while doing bench press, squat or deadlift: one limb will always be dominant and the other will be laggard).
Superior range of motion as well as the inherent instability of dumbbells force the entire body to brace and stabilize the load in addition to lifting.
+ as
@bigb123 mentions, the size convenience factor is tough to overlook.
I wanna buy weight lifting items but there are so many items available in internet with different brands , and even 2kg dumbbells is expensive ,
I wanna buy some weight lifting items
Suggest me some , and tell me which one you have
The purpose of weights lies only in two things:
1) the mass of the object: a 2 kg object (suitable for one exercise) is lighter than 5 kg (suitable for another exercise)
2) the shape of the object: should be convenient to hold and carry out your exercise
I have bought the dumbell plates + rods + nuts from roadside which is available at Rs per kilogram rates.
Any additional spending is not going to improve any utility of the item apart from the following:
1) poor quality cast iron plates can break if dropped; pressed steel will not (though I wonder if you will get those)
2) rubber coated plates will hurt your feet less when you drop the weight on them, compared to non-coated ones (of course the chance of breakage is also less)
3) long spindle rods will allow you to stack more plates and do heavier weights
4) the thicker the rod, the more difficult to grip for long (on the other hand it could be a good exercise to improve grip strenght)