supply of low angle perspexlow angle perspex,low angle perspex wedge attachment of 15 degree suitable for 20mm dia. normal singl e crystal probe make: modsonic for usfd machine. note: - the supplied parts should be of modsonic m ake only to maintain compatibility with modsonic make usfd machine. [ warranty period: 30 months after the date of delivery ] ] , low angle perspex wedge attachment 17.5 degree suitable for normal probe- 20mm di a. make: modsonic for usfd machine. note: - the supplied parts should be of modsonic make only to m aintain compatibility with modsonic make usfd machine. [ warranty period: 30 months after the date of delivery ] ] , normal single crystal probe 1.25 mhz, crystal size: 20 mm dia. make: modsonic, for usfd machine. note: - the supplied parts should be of modsonic make only to maintain compatibility wit h modsonic make usfd machine. [ warranty period: 30 months after the date of delivery ] ]