The past six months have brought with them some stellar performance from industrial supplier Fastenal ( FAST). Shares of the $15 billion firm have climbed more that 15% over that time period, vs. gains of just 9% from the S&P 500. But that hasn't changed short sellers' opinions of the stock. As I write, Fastenal sports a short interest ratio of 13.1. Fastenal's biggest benefits are its huge geographic footprint and a catalog that boasts more than 410,000 types of fasteners and more than 585,000 maintenance and repair products. In the hugely fragmented industrial supply business those factors keep Fastenal's abilities head and shoulders above smaller firms, and they give FAST the ability to wrangle lucrative national accounts for larger customers. Even with those attributes, industrial supply is still very fragmented, and Fastenal has growth opportunities if it can tuck-in smaller successful rivals into its business through acquisitions. Financially, Fastenal is yet another firm that sports a spotless balance sheet position. While the company only carries around $80 million in cash on its balance sheet, it's also debt-free. That means that this firm doesn't have as many financial obligations to weigh down its returns each quarter. As the industrial sector continues to heat up, so too should Fastenal's profitability. Short sellers beware.