The delrin shells have become the preferred beads of many players, due to their vibrant colors, durability, and distinctive (loud) clack. Delrin is a durable material, with a warm and comfortable feel. Although it is technically a plastic, it feels more like wood to the touch, and is extremely durable. Although it is possible to crack these shells over time, it is extremely uncommon, and they should hold up to extended use. The material cannot be injection moulded, and these shells have been precision machined--just like their metal counterparts.
The delrin shells are too light to play well on their own. This Boss Delrin Begleri includes a set of Stainless-Steel Core Beads
Delrin Boss Shells: 3.5mm top bore; 4.6g each (empty); 21mm diameter
Core Beads: 3.7mm top bore, 7.5g each, 12mmx12mm