Lengths from 50FT (15M) to 300FT (100M). The Keson OTR (open type reel) series of measuring tapes finds the most favor in industrial/construction applications, although others often select it. The Keson MC (closed metal case) is most often selected by realtors and appraisers because: 1)Its compact size makes it easier to carry in pocket, purse or briefcase. 2)The closed case keeps your clothing or other carrying location cleaner...any dirt or moisture that gets on the tape ends up inside the case, not inside your pocket. The Keson K-line series is designed as an economical alternative to the OTR series of measuring tools, and features our longest tape: 330ft! Keson OTR (Open Type Reel) Tape Measure Fiberglass Tape Measures, Closed Metal Case K-Line Fiberglass Tapelines. Great quality, Great prices! Fiberglass Measuring Tape Refills