I've been using the MKSY Core Coaster for a few weeks now, and it's a mixed bag. On one hand, it's super portable and doesn't take up much space in my tiny apartment. The golden ratio design looks sleek, and the multi-directional movement is great for targeting different muscle groups beyond just abs—I definitely felt it in my shoulders and arms too!

However, the small wheel size (seriously, like a quarter!) makes rolling unstable on hard floors. The non-attached casters are a nightmare—they swivel unpredictably mid-exercise, causing the platform to tip sideways. I had to constantly readjust my form, which ruined the workout flow. Also, that 'ergonomic' handle? Not so comfy after 10 reps—my palms were sweating and slipping.

The included knee pad is basically useless; it's just thin foam over hard plastic. I had to layer two yoga mats underneath to avoid bruising my knees during kneeling rolls. For seated or standing exercises though? Surprisingly effective! Just don't expect gym-machine stability.

Final verdict: It works if you're patient with its quirks, but the caster design needs a major overhaul. At this price point, I'd recommend saving up for a sturdier ab wheel with larger, fixed wheels instead.