I love this item because I can watch the changing contours of sand in the upper and lower chambers of the hourglass as it empties. It's mesmerizing.
Initially I was reluctant to purchase this item because I wanted an hourglass with a wooden frame around the glass for added protection but I'm very happy that I purchased this item instead because with a wooden frame, I wouldn't have been able to see as much of the changing contours of the sand in both chambers as the sand descends.
Move the hourglass around as the sand descends and watch the effect it has on the mound of sand in the lower chamber.
With a wooden frame, the focus is on the outcome: when the time is up. With a frameless hourglass, the focus is on the process: the movement of the sand.
Get at least one of each type. I never thought their impressions on me could be so different.
A second bonus of this item: It's natural sand. The grains are not of a uniform color. The grains have a range from brown to beige and some sparkle. It's more beautiful than the colored sand.