PIRASTRO KONTRABASS TELİ PERMANENT SET. Pirastro makes good double bass strings, called "Permanent". These are primarily a classical (bowed) upright bass string, but some Jazz players also use them. For some basses, the Permanents can be a little ''too much'' for their bass. That is, the strings have a little added tension which can have add more punch to the attack (or "pop") of the string from the bow, but the tradeoff there is that while they have warm tone, the seem just a bit more stiff than the traditional Flexocor bass strings. (The slight added tension can do that). You can use the whole set of Permanents (as is often the case) or you can supplement a set of Flexocors (A, D and G) with the added Permanent E string.