"The Martian"

Solid stainless steel, 473 grams of it, and Satisfyer publishes a 15 year guarantee on it. "The Martian" is double ended, 21 centimetres long and 3 centimetres across, with one end drawn into a smooth curve and the other shaped into a run of beads, so one piece gives you two quite different sensations.

If you already know what you like and want something with real weight behind it, this is where steel earns its place. You rock it rather than thrust, and the heft supplies the pressure your wrist would otherwise have to. It's rated IPX7 waterproof, so the bath is fine.

Steel takes temperature well. Stand it in warm water or leave it in the fridge for a few minutes before you start. Use plenty of water-based lubricant, because the material has no give in it at all, and take the beaded end slowly.