A discrete Hardy-type inequality ( ∑∞ n=1( ∑n k=1dn,kak)un) ≤ C( ∑∞ n=1 a p nvn) is considered for a positive “kernel” d = {dn,k}, n,k ∈ Z+, and p ≤ q. For kernels of product type some scales of weight characterizations of the inequality are proved with the corresponding estimates of the best constant C. A sufficient condition for the inequality to hold in the general case is proved and this co...