Bob from SWISCO responded:
October 29, 2023
Thanks for posting. Good question. The difference between these two sets of operators is the shape of the gear arm. The 39-089 and 39-090 have a 'Z' shaped gear arm, whereas the 39-187 and 39-188 gear arm has an extra bend, making a 'W'. See the images below of the 39-089 and 39-090 that highlight this difference. Let me know if you have other questions. |