What are those trailer wheel jack/red little ramp things called pls??

[prudunce]

After having a puncture on trailer and not having a jack to lift trailer high enough,i must buy a jack! What are thoses little red plastic rampy/jack things called.Think u drive up it wiv 1 wheel & can change tyre wiv horse on-board ?any ideas pls??thankyou

 

[lucemoose]

trailer aid, i think they are yellow