Manufactured by Islok Handelsmij, Zwolle, Marsweg 9.
Active from 1949 or earlier, the firm built mostly carrier bicycles. Their powered machines were fitted with JLO and Royal Enfield engines.
According to a 1954 article in "De Nederlandsche Rijwielhandel" which shows an aerial photograph of a quite substantial factory, some of the carrier bicycles were fitted with auxiliary engines of 98 and 118 cc, and the motorcarriers had 145cc JLO or 150cc Royal Enfield two-stroke engines with kick starter. Other models had JLO 200c and 250cc powerplants, swinging arm rear suspension, and reverse gear.
Sources: transportfiets.net; tradesmansbike.wordpress.com; mo-ped.se.