Shares of BLS Polymers are set to make their debut on the BSE and NSE on Tuesday, with strong investor sentiment reflected in the grey market. The IPO is commanding a grey market premium (GMP) of around 45%, indicating expectations of a strong listing gain over the issue price.The Rs 255-crore book-built issue comprised an entirely fresh issue of 1.70 crore shares. The company had fixed the price band at Rs 142-150 per share, with a lot size of 100 shares.