The Thwack is made of two pieces of smooth silicone, joined together with flawless precision, with nary a gap nor a mismatched edge to be found. Only a subtle visible line around the outer edge gives it away as not being one solid piece, and it's doubtful that it will ever come apart. If you have multiple partners, you may find that one of the best things about this paddle is that, unlike leather or wood, silicone can be fully sanitized between uses, so you need not worry about what might get on it.
Looking at it from the side, there is a taper where the handle meets the striking surface, so the 1/4" business end flares up to a 1/2" thick handle. There is a hole in the end of the handle where you can add a strap if you want to. Due to its lack of rounded edges, the handle might not be entirely comfortable for all users to grip after an extended time of use, particularly for those with smaller hands.
From a straight-on view, the 5.5" long handle is contoured from 1.75" to 1.25" wide, while the striking surface is simply a 3" x 6.25" rectangle with rounded corners. People with large hands will have no trouble getting a firm hold on the generous length of the handle, and those with small hands can simply shift their grip up toward the narrower part for more stability.
Overall, the paddle is just under 12" long, so it wouldn't be difficult to find a place to store it or hide it.