The W20 improves on the specification of the W10 only marginally, adding only a 7-megapixel sensor, a larger internal memory (22MB 
rather than 10.5), higher maximum sensitivity (1600 ISO over 800 ISO) and compatibility with the new SDHC (High Capacity) memory cards. Other than those changes the two camera are very similar. Even the body design is virtually identical, although the W20 adds a slight flare to the front of the case on the handgrip side, making the camera slightly more secure to hold. Unchanged are the 2.5in 115,000-pixel monitor, the 3x optical zoom non-protruding lens, and the ability to survive immersion in water to a depth of 1.5 metres for up to 30 minutes.
The W20’s body is mostly plastic, with an aluminium inset front panel. Build quality is very good, and although it doesn’t have the shock-proof abilities of the Olympus mju 725 SW it still feels sufficiently robust to survive a few knocks. The shape is smooth and sleek with no protrusions to catch on clothing or get snapped off. TrustedReviews - Pentax W20 Waterproof Camera