I was told the MD 1000 seatpost is 30.4. If
@Terry777 has a caliper he could verify. I purchased a Suntour SP12 NCX. It comes in 350 & 400mm lengths. I got the 27.2 400mm, a heavier spring and a 27.2 to 30.4 adaptor. The Suntour places the rider a bit farther from the bars than the Thudbuster. Being tall, that's not a problem for me and I liked the Suntour's spring tension adjustability as opposed to replacing the ELASTOMER on the Thudbuster. Also, all of these add 2"- 4" to the seat height so keep that in mind. I have the Kinekt 2.1 on another ebike and it's OK but if I had a do-over I think I'd get the Suntour as it is much less expensive and provides more adjustability and cushion. You can get adaptors at any good bike shop or online.