De or het koopaanbeveling?

The correct Dutch article is:

de koopaanbeveling

Rule Words ending in -ing: almost always de. See the rule

How to use koopaanbeveling

the koopaanbevelingde koopaanbeveling
this koopaanbevelingdeze koopaanbeveling
that koopaanbevelingdie koopaanbeveling
our koopaanbevelingonze koopaanbeveling
your koopaanbevelingjouw koopaanbeveling
every koopaanbevelingelke koopaanbeveling
which koopaanbeveling?welke koopaanbeveling?
a big koopaanbeveling / the big koopaanbevelingeen grote koopaanbeveling, de grote koopaanbeveling