They have internal teeth that provide a good grip on the object

as directly stated in the manufacturer's documentation: DSX 80

This micro soldering iron set

Physical size (L x W x H): 25

Den bruger M12-gevind

SPS Sikkerhedstester AC 100V- 5,5kV/0-20mA/DC 100-6kV/0-20mA med socket Unit(s):PCS They have internal teeth thatUniversal Safety Tester S 6600H The S 6600H from SPS ELECTR is a desktop universal safety tester for electrical safety tests. The device performs AC and DC high voltage tests, insulation tests, ground bond tests, as well as resistance and continuity measurements within the operating ranges specified by the manufacturer. Technical Overview AC high voltage test: 100 V 5,500 V, current range 020 mA DC high voltage test: 100 V 6,000 V, current range 020