Lewis industrial tower Certified to the very latest BSI Kitemark in respect to BSEN 1004 (Class 3) Fully compatible with SGB BoSS Towers Integral ladders with comfortable D section for secure footing. I Aluminium Tube: 50.8mm Tube with a 1.8mm Wall thickness. Self-closing trapdoors & Simple wind lock clips Safe working load of 275kg per platform level up to a maximum of 950kg per tower (including self-weight).