We have one of these, Amazon and it is good but not worth the price. It comes with marbles to weigh it down and it is pretty comfortable to sit on but I would look at that $30 one that was previously posted and add your own marbles.

I think most have a variety of heights. I bought this weighted pillow for my son to sit on, but I even use it sometimes when I’m too hot and want to be a little further out of the water. The pillow has stones on one side to make it sink.

[KenleyHotTubBoosterSeat-...https://www.amazon.com/dp/B07DL5M7R4?ref=ppx_pop_mob_ap_share](KenleyHotTubBoosterSeat-...https://www.amazon.com/dp/B07DL5M7R4?ref=ppx_pop_mob_ap_share)

Of course the one we have is not available at this time. Just like everything else. But I found a few others with good ratings. I’ll link below.

Kenley Hot Tub Booster Seat - Submersible Weighted Spa Pillow - Washable Cushion Cover https://www.amazon.com/dp/B07DL5M7R4/ref=cm_sw_r_cp_api_glt_fabc_5AT72TH1XV8FT5VWHBDD

STAR SPLASH Hot Tub Booster Seat, 15 x 12 x 5 Inches - Hot Tub Pillow with Non-Slip Micro Dot Bottom and 6 Weighted Sections - Quick Dry Bath Accessories for Indoor or Outdoor Hottub https://www.amazon.com/dp/B08QW5RHMW/ref=cm_sw_r_cp_api_glt_fabc_AVEB9XBME03J2HYXCB39?_encoding=UTF8&psc=1