My job entails frequent travel, staying in noisy hotels. I often have to sleep at odd hours of the day and the noise from service rooms, lifts, room service trolleys, housekeeping staff, and loud hotel guests drives me mad! I have tried sleeping tablets and other ear plugs, but these are fantastic! They really do form a seal and block out nearly all noise. I got to my hotel room dismayed to hear drilling and hammering and thought I would never be able to sleep, however I got THE BEST sleep once I had inserted these ear plugs. They do get less effective once used a few times as the seal is lessened however they are still highly effective. Even if you only use each pair for the recommended amount of time(5 uses), a pack last a whole month with daily wear - a bargain for any insomniac! I thought they might not be very comfortable, but I neednt have worried - I had no problems at all! and the fact that you dont have to push them into the ear canal itself is very appealing for a frequent user! I have never written a review before, but these are so good I had just had to pass this on! Insomniac no more!