i/we have started proprietorship firm name of 'NITESH BUFFING WORKS'. Specialist in - pharma GMP model equipment's finishing work, S.S. Buffing, 350 Great Dull polish, 420 Great mereal polish. so i/we am/are going to registration of GST. but i have no idea which HSN/SAC code, which services and how many percentage of GST rate applicable. please reply.