supply of 1. double crystal transducer for normal beam scanning 15mm x 15mm square of frequency 4 mhz (including connecting cable of two meter length bnc sockets). make: eec or its equivalent. 2. double crystal transducer for normal beam scanning 20mm x 20mm square of frequency 4 mhz (including connecting cable of two meter length bnc sockets). make: eec or its equivalent.1. double crystal transducer for normal beam scanning 15mm x 15mm square of frequency 4 mhz (including connecting cable of two meter length bnc sockets). make: eec or its equivalent. 2. double crystal transducer for normal beam scanning 20mm x 20mm square of frequency 4 mhz (including connecting cable of two meter length bnc sockets). make: eec or its equivalent.,double crystal transducer for normal beam scanning 15mm x 15mm square of frequency 4 mhz (i ncluding connecting cable of two meter length bnc sockets). make: eec or its equivalent. [ warranty period: 3 0 months after the date of delivery ] , double crystal transducer for normal beam scanning 20mm x 20mm square of frequency 4 mhz (i ncluding connecting cable of two meter length bnc sockets). make: eec or its equivalent. [ warranty period: 3 0 months after the date of delivery ]