The 
Monument MP1600 Toilet Plunger is a high-performance, patented bellows-design plunger specifically engineered to clear blockages in toilets and gulleys by directing maximum force around the U-bend. 
Key Features
Bellows Design: The unique, patented bellows design allows for more cubic centimetre water displacement than traditional cup-style plungers, effectively focusing force on the blockage.
Targeted Use: It is specifically designed with a funnel nose to fit tightly into a 90-degree bend in a toilet pan, though some reviewers note that a tight seal can be tricky in some modern pans.
Durable and Hygienic: Manufactured from durable plastic, the plunger is easily cleaned and will not rot. The handle is also removable for easier cleaning and compact storage.
Versatility: While optimal for toilets and gulleys, the focused design can be less effective on flat-bottomed sinks or showers where a seal cannot be easily formed.