I bought a sampler pack with both GSB and Nacet. GSB lasted twice as long for me. However, when I bought a pack of 100 GSB (even checked the serial number online - was correct). They were really bad. I tried two or three packs and all felt like a weak shark blade (not as nice) - stretched and pulled the skin. I ordered a new batch (says 2021) from Canada. Let's see if they do the job.
