The new cartridge tattoo needle by TatSoul has some nice features.  Having used their quality, smooth running needles in the past I had to try this cartridge with a soft silicone finger ledge. It's like a squishy pencil holder. 

What I found a huge plus is the way the Envy finger ledge integration fits into the pen style tattoo machine making it easy for the way I wrap my machine for cross-contamination prevention. 

Another style needle cartridge is the Vertix tattoo needle cartridges.  Both the TatSoul and Vertix tattoo cartridge needles are great quality, have a lip on the cartridge making it fit nicely up to the edge of the machine tip, and they both have a membrane that prevents the backflow of ink into the machine. 

 To your PMU success,

PMU Artist & Needle Specialist
Inside Needle Knowledge, I.N.K.