I personally wouldn't buy these toys, but if you do buy them and want to use them, I'd recommend using a condom even if you're the only person who will be using them. It's just not a very safe material. Here is the information about the material, from the Sex Toy Materials Index:


SensaFirm

Material safety
2

Components
Thermal plastic elastomer variations

Properties
Compounded to mimic real skin. The high molecular density of these materials allows flexibility and resilience.

Hygiene And Maintenance
These materials are very porous, making it difficult to clean and easy for germs and dirt to hide. Should be protected with a condom. They are extremely sensitive and should be cleaned following every use with warm water and toy cleaner or antibacterial soap. Toys made of these materials should be stored in dark cool place.

Lubricants
Water based only