Review on 🔧 iplusmile Brass Knurled Nuts - Threaded Heat Set for 3D Printer & Projects (100pcs, M3 Thread, 3x4.6x5.7mm) by Dave Branch

Pattern appears to be better than straight lines or knurling for pull out resistance and torque. The other inserts I was able to find using this pattern were much thicker, making it a little less worth using M3 screws. I measure their length 5.7mm, base diameter 3.9mm (smooth part inserted first), diameter 4.5mm. first template/knurl diameter 4.3mm between templates and 4.6mm second/last template. They melt perfectly into a 4.0mm hole, the smooth/thin section makes positioning easier and means they won't slip when the plastic melts like other knurled/patterned inserts either side of the edge. Highly recommended.