The Women's Rugby Super Series tournament will be harder than a World Cup, according to England captain Sarah Hunter.
The top five teams in the world all meet in San Diego, with Grand Slam champions England opening their campaign against USA on 28 June.
Simon Middleton's side then face Canada, France and world champions New Zealand in the round-robin tournament.
"It's incredible for us to have this opportunity," Hunter told BBC Sport.
"In some respects you could say it is harder than a World Cup.
"You probably wouldn't play the top five sides in the world during a World Cup campaign, so it gives us a great chance to actually see where we are at."
England breezed to a Six Nations Grand Slam earlier in the year, but Hunter expects the standard of competition to be significantly higher in California this summer.
"We did have a great Six Nations, and we can only play the opposition in front of us, but now we are going halfway across the world and playing the best teams that there are," she added.
"It's our chance to find out where we are and how we then need to move on in terms of looking at the big picture [at the World Cup] in two years' time."
Middleton has named a 28-strong squad for the Super Series, with Hunter leading a group shorn of some experienced players through injury.
Fly-half Katy Daley-McLean, centre Rachael Burford and wing Jess Breach have all been declared unavailable.
However, centre Emily Scarratt is among those to return, while uncapped pair Chloe Edwards and Clara Nielsen are both named as Middleton looks to build depth into his squad.
"We need to be coming off the summer tour with a really clear picture of what our squad is starting to look like in terms of the World Cup," Middleton told BBC Sport.
"The Super Series will provide us with a perfect platform to see exactly where we are."
England's Super Series matches
Friday, 28 June: England v United States (21:00 BST)
Sunday, 7 July: Canada v England (01:15 BST)
Wednesday, 10 July: England v France (22:15 BST)
Sunday, 14 July: New Zealand v England (21:00 BST)
All matches will be played at the Chula Vista Elite Athlete Training Center in San Diego except the final game against New Zealand, which will be played at University of San Diego's Torero Stadium.