The present invention provides a system for lyophilization comprising one or more delivery containers, e.g. syringes, and a cover plate, which covers them during lyophilization. The cover plate includes a lid region and one or more protuberances, which project perpendicularly from the lid region and fit delivery containers such that the protuberances are not in complete and continuous contact with sidewalls of the delivery containers. The cover plate permits the escape of vapor from the delivery containers during lyophilization process through an annular gap between each protuberance and a sidewall of each container when the cover plate is resting on the top of the delivery containers. At the same the cover plate prevents the escape of lyophilizate, in particular a pharmaceutical, from the containers during lyophilization.