Threaded Step Probes If you need further information please contact us at this email address, or download the Equip-Test Catalog. SPT1000 – 100 Mil / 2.54 mm – Threaded Step Probes SPT1001 – 100 Mil / 2.54 mm – Threaded Step Probes SPT1002 – 100 Mil / 2.54 mm – Threaded Step Probes SPT1600 – 160 Mil / 4.00 mm – Threaded Step Probes SPT1601 – 160 Mil / 4.00 mm – Threaded Step Probes