Stays and fork have domed ends, so Reynolds tubing. Columbus SL or SP was also available. They have flat ends. The SLX frame looks very different: Everest instead of Bocama lugs etc. The Professional was hand built in Batavus small frame shop in Heerenveen, The Netherlands. They are comparable with the top end frames of the Gazelle Champion Mondial program. Batavus supplied the KNWU Dutch national team with Professionals.
SLX frame in KNWU livery >> https://www.classicsteelbikes.com/produ ... ecord-nos/
SLX frame in KNWU livery >> https://www.classicsteelbikes.com/produ ... ecord-nos/