Block rubber is a generic term for a way of presenting rubber for marketing – rubber of many different types can be crumbed and compressed into blocks or bales, typically weighing 33 or 35 kg. Thus, block rubber can have characteristics across a wide range of properties. Because of advantages in processing and convenience in handling, more rubber is traded as block rubber than rubber in any other form. Among the TSR rubbers, the addition of hydroxylamine, denoted by CV, standing for controlled viscosity, or the absence of hydroxylamine differentiates otherwise closely similar grades. Hydroxylamine may be added either at the latex stage or to crumbed rubber (i.e. after coagulation). All TSR rubber is shipped as blocks wrapped in polyethylene (polythene). These blocks are usually shrink-wrapped on pallets, usually with a net weight of one ton, but sometimes with a net weight of 1.05 tons.