I'm a fan of Modified slims, and those are great. I like the way you matched the grains; well done.
When I have made some with modified, thin diameter center bands, I have had issues when taking the pen apart to replace the cartridge - extreme care is needed to avoid cracking the center-band when reassembling. Most users do not pay attention to this and end up cracking the center-band. I have since coated the inside of the center-band with thin CA to stabilize it a bit.
Beautiful work. Thanks for sharing.