The Suntech Field Master was the first 3-position zoom rod sold in the US. The Field Master 39 can be fished at 3.2, 3.6 and 3.9m. If you do not fish extremely overgrown streams, where you might want a rod even shorter than 3.2 meters (10'5" by actual measurement), the Suntech Field Master 39 may cover all the lengths you'll ever need.
When I first ordered the Field Master 39 (back in 2012) I had been looking for a rod that had all the sensitivity and feel you get from a rod that doesn't have a cork grip, but also had bend characteristics that placed it squarely in the middle of the "tenkara rod" range. The Field Master 39 did that, and did that at three different lengths! I couldn't have asked for more.
There is a big difference between what I knew then and what I know now. Other than the few Daiwa tenkara rods I also imported that year, all of the tenkara rods available in the US in 2012 were sourced in China. The Chinese had no history of tenkara fishing. They made rods for bait fishing. The earliest rods in the US had actions that put them squarely in the middle of the keiryu rod range, so in retrospect, it was no surprise that the Suntech Field Master, which is a keiryu rod, had an action squarely in the middle of the "tenkara" rods that were available here at the time.
I would bet that all of the people who purchased Field Masters in the early years used them exclusively for tenkara fishing rather than keiryu fishing, though. Of course, many if not most also fished bead head flies, which the Field Master does quite well.
It fishes bead heads well because fishing bead heads, particularly heavy bead heads, is really pretty similar to keiryu fishing. And although the Field Masters do quite well with a size 4 tenkara line, they really are better at keiryu fishing than they are at tenkara fishing. However, they are still better at fishing bead head nymphs than the average tenkara rod.
Field Master II 39
Length extended: 10'5", 11'8" 12'8"
Length collapsed (with tip cap): 21"
Weight: (with tip cap) 2.8 oz (without tip cap): 2.5 oz
Recommended Tippet: 7X - 6X
CCS penny measurement: 24; 26; 28