I own a Specialized E-Bike and I had a tube failure. This was the closest fit that I found on BTD's website. I compared the tube to the failed original Specialized tube on the bike and it was very similar in build and weighed the same. The 700, 45-50 size is perfect for the 700, 47 sized tires on the bike. The threads on the Kenda tube Presta valve are 60 mm whereas the Specialized tire came with 40 mm long threads. It is a minor, visible difference.
The original tire failed I believe due to a faulty, removable Presta valve. The failure mode was explosion.
I intentionally sought a different brand of tube due to the failure even though I believe Specialized makes a great bike. The original tire was a 700, 32-50, 40 mm. Since Kenda's size was the narrow width band of 45-50 I'm hoping this may be helpful in avoiding another problem. So far, 2 months later no flats or problems.
I purchased these as I needed a tire with better traction across a lot of riding conditions. Was a little concerned about if they would roll too slow. Have about 300 miles on them now and these tires have fantastic traction! You can really depend on them when railing into a corner fast and on rough stuff. They are a little slower then a tire that is made for speed but then again made for speed tires do not have good traction. I noted when you get over up to about 4 or 5mph these tires roll very fast! I was very surprised at how fast they roll for a aggressive tire. They are holding up very well and the weight is no more then some other tires that are only 2.3 in size.
I live in Hemet Ca. My vintage Schwinn requires 85-90 PSI. Sheep's Head Thorns are everywhere here. I can't count the number of times my "good times" were cut short with needle like punctures. Since I switched to the 27"- 1 1/8" Kenda Thorn Resistant Tubes "not available at retail bike shops" I haven't had a problem since. HEADS UP: Add 1.5 oz of Stan's No Tubes for good measure. Stan's works equally as well weather you've running tubeless or tub tires. Sincerely