Butyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Polyisobutylene, also known as "PIB" or polyisobutene, (C4H8)n, is the homopolymer of isobutylene, or 2-methyl-1-propene, on which butyl rubber is based. Butyl rubber is produced by polymerization of about 98% of isobutylene with about 2% of isoprene. Structurally, polyisobutylene resembles polypropylene, having two methyl groups substituted on every other carbon atom. Polyisobutylene is a colourless to light yellow viscoelastic material. Flexilis Pvt Ltd is authorised stockist and importer of Exxon Butyl rubber in India. Butyl rubber is used as raw material for making tyre, inner tube, cycle tubes, conveyor belt, automotive vibration control, pharma stoppers, seals, construction sealant, hoses, gasket, sealant tapes, bladder, spouts goods, tank lining, vlave cement, flooring adhesive, healthcare, condenser padding tires, inner liner, roofing material, rubber compound, ball bladders, gas mask. Butyl 268 (IRR) Bromo Butyl and Chloro Butyl are commonly used type.