No matter if you’re dermarolling or stamping, you have to replace the needles or the device itself after 8-10 uses. The needles get dull and can bend which causes trauma to your skin. There are high quality stamps for about $15-$20
The higher quality pens usually cost more but come with interchangeable attachments that’s usually way more. These stamps are less than 15 dollars, that’s why the use is so low.
1.5 mm for hair regrowth but only use that once every 10-14 days. Use a 0.5-1mm twice to three times a week for hair maintenance. 0.5 for beard twice to three time a week.