tender for hygrostat in duct design with internal adjust knob measuring range 30-100 rh measuring accuracy +/-4 sensor length 220 mm high grade steel weight of0.7 kg confirming to rdso spec. no. rdso/pe/spec/ac/0061/2005 [rev.- 1] as per sidwalpart no. sr-075-1022 & galltec make model no. hg80i suitable for lhb ac coaches .