25/07/2021
HOW TO DISTINGUISH AN RH91 FROM AN RH93:
Most RH91s have a serial number starting 0 (below 1,000) whereas most RH93s have a serial number starting with 1 (1,000 and above).
These two images should help you to distinguish. The end of the cylinder block on the RH91 is flat, with no safety catch on it. The end of the cylinder block on the RH93 has a domed shape with an integral automatic safety catch.
Early RH93s had a flush safety button, whereas later ones had an elevated lever. This was following complaints from users who struggled to operate the flush button in cold conditions in the field, particularly when wearing gloves, However, the lever also had its detractors as some found this more difficult to use with larger telescopic units, especially those seated more aft.: