Coarse Sand (Minimum Zone- Iii), Specification As Per Clause -30F-Is-6586-1972/ Irs Bi/2 021(Reprinted -2008),Grain Size Of ( Sharp Coarse Sand) Should Be Between 600 Micro Meter - 1700 Micro Meter & A Minimum Of 40 Percent Should Be Retained On A 850 Micro Meter Sieve, Conforming To Is-460(Pa T-1)1985. [ Warranty Period: 30 Months After The Date Of Delivery ] ]