In the depths I accept a width of 5 cm and a length of approximately 38 cm, so it is still a good idea to start with the small ones, the large ones are 6.4 x 41.2 and the small ones are 32 x 5.5 cm
if you are not sure, which size your arsecunt can swallow, take the smaller one. And if it fits perfectly you may insert a second plug to get the full feeling and buy the larger one later. I always like the feeling when I have to piss off without controll when the plugs are stimulating my inside strongly and my arsecunt is pulsating after releasing the toys