The SPI Supplies Style #4a High Precision Tweezers are produced in Switzerland and are of the same high quality and workmanship as the Style #4 tweezers. The difference between Style #4 vs. 4a might be subtle, but it is significant. The "taper" on the Style #4 is sharper than for the #4a. Hence the tips on the Style #4 are "sharper". But they also will wear out faster (or bend and become damaged easier). Putting it another way, Style #4a with a taper not so sharp, results in tips that are stronger and more robust. But the downside is that one can not pick up electron microscope grids or other fine objects as easily.
On the other hand, we do have customers who have mastered the art of using Style #4a for picking up electron microscope grids and once they have done that, they do indeed have tweezers that will "last longer". But we believe the typical researcher, especially one picking up electron microscope grids, would be happier using Style #4 or perhaps even better, Style #5.
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