Hammer Test HT 225 mechanical rebound hammer is the product of direct experimentation on different types of concrete. Used appropriately and following the correct procedures, this is a valuable instrument for testing and evaluating the quality of concrete, ensuring totally reliable results. 1CENTER ROD IS MADE FROM IMPORTED MATERIAL, HIGH ACCURACY AND DURABLE RESISTANCE. 2The shell is made form high Aluminum or high polymer material in order to perfect protect instrument from damage and extend use life. 3Pointer slider is outside structure, its friction can be balance well and easy to be adjusted so that we can make sure that the instrument is accurate. Compared with other suppliers in the line of business, the product is more accuracy, good quality, and best price and longer use life. SPECIFICATIONS: Nominal kinetic energy : 2.207J (0.225 kgf.m) Flip tension spring rigidity : 7.84N (0.80 kgf) / cm Punch advance for impact hammer : 75 mm Impact surface hardness value between impact hammer and rod : HRC59-63 Maximum breakout friction of pointer system : 0.49-0.78N(50-80g) Mean-value of steel-anvil rating of concrete test hammer : 80+/-2 Standards : ISO/DIS 8045, EN 12504-2, ENV 206, DIN 1048 part 2, ASTM C 805, ASTM D 5873, NFP 18-417, B 15-225, JGJ/T 23-2001, JJG 817-1993 Dimension : 60 x 280 mm