The Façade Construction Quality Foundation (Stichting Kwaliteitscentrum Gevelbouw (SKG)) is an independent body that has been working to ensure that safety products meet strength and durability requirements for more than 35 years now. The SKG hallmark is awarded to each approved individual product. The following classifications are possible:

STANDARD:

SKG*, not independent. These are products that will slow down burglar entry by a minimum of three minutes, in combination with other burglar-resistant provisions.

HEAVY DUTY:

SKG**, independent. These products individually slow down burglar entry by a minimum of three minutes.

EXTRA HEAVY DUTY:

SKG***, independent. These products individually slow down burglar entry for a minimum of five minutes.