Screw caps or "Stelvin caps" are closures made only from aluminium material that threads onto the bottleneck. They are the predominant closure used by Austrian, Australian and New Zealand wineries. This can be attributed in part to the New Zealand screw cap initiative which promotes the use of screw caps instead of cork. Screw caps form a tighter seal and can keep out oxygen for a longer time than cork. These benefits aid in maintaining the wine's overall quality and aging potential. Michel Laroche of Domaine Laroche noted that this played a role in his decision to adopt screwcaps. "Extensive quality tests show convincing results: apart from protecting against cork taint, screwcaps are also beneficial in the aging of wine, particularly preserving the aromatic freshness."