Part No: M20F15-IRIS Probe 1.5" focal length 20MHz
https://store.thesonic.org/shop/part-no-m20f15-iris-probe-1-5-focal-length-20mhz-755
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Part No: M20F15
IRIS Probe 1.5" focal length 20MHz
IRIS Transducers Composite crystal, Outer Diameter: 3/8 Inches Element Diameter: 1/4 Inches Probe Frequency:15MHz Focal Length: 1.5 Inch (38.1mm)