Check the listing for details. Choptima Pull Dump Retention Ring – Aftermarket 3D Printed TPU Upgrade. Condition: New. Listed at 20.00 USD. Designed and test-fit on my personal Choptima unit. I designed this part for my own unit after the upgraded pull dump never sat quite the way I wanted. The TPU version has just enough flex to make installation easy while still holding shape once in place.