RIOCOCO PCM 4 in. x 4 in. Coco Starter Blocks - Pack of 275RIOCOCO PCM Starter Blocks Propagate faster and produce healthy plants organically. Excellent water holding and equal distribution of water throughout the starter block ensures optimum management of the air and water. PCM Starter block is made from 100% coir fiber without fine dust particles and its compressed to a square disc and packed in a biodegradable cellulous sack. The airy and fragile structure is maintained throughout the propagation cycle,