SPINERA MATERIAL HDDS - HIGH DENSITY DROP STITCH - single layer dropstitch fabric - knitted - 90% of sup use this kind - weight and stiffness good - works good for sup with 15cm thickness PVC SHEET FIRST RAIL SECOND RAIL BASE CONSTRUCT DLT - DOUBLE LAYER TECHNOLOGY - double layer dropstitch fabric - knitted - fusion double laye - MSL - more stiffness - holds more weight - fabric is more durable against abrasion and as a matter better for air tightness EVA PAD REINFORCED LAMINATED PVC FIRST RAIL SECOND RAIL BASE CONSTRUCT SL ULT - SINGLE LAYER ULTRA LIGHT - single layer dropstitch fabric - woven - still it is a little more stiff as HDDS but less as DLT - 25-30 % lighter compared to HDDS - very light and max stiffness and durability PVC SHEET FIRST RAIL SECOND RAIL BASE CONSTRUCT DL ULT - DOUBLE LAYER ULTRA LIGHT - double layer dropstitch fabric - woven - same as SL ULT but with 2 layers - very light and max stiffness and durability EVA PAD REINFORCED LAMINATED PVC FIRST RAIL SECOND RAIL BASE CONSTRUCT