The Rs 1,500 crore initial public offer (IPO) by Pune-based specialty chemical firm Clean Science and Technology (CSTL) will open for subscription on Wednesday. The issue, which is slated to run between July 7-9, is priced in the range of Rs 880-900 per share and is entirely an offer for sale. The prime purpose is to enhance visibility, brand, provide liquidity to existing shareholders and achieve the benefits of listing shares on stock exchanges.