You don't need to get Vivitar brand eyepieces to get additional ones for your telescope. I'm not sure of the specifications for this particular telescope but in general they come in two barrel sizes for the eyepieces. The diameter of your eyepiece is probably 0.965" but could come in the more standard 1.25". You can measure the diameter and determine this quickly.
Once you know the diameter to shop for you can look for the focal length of the eyepiece you wish to purchase. They are rated such as 4mm, 10mm, 25mm, etc. The smaller numbers give you higher magnification. You can calculate the magnification by dividing the telescopes focal length by the eyepiece focal length. For example, let's say your telescope is has a focal length of 360mm and you have an eyepiece rated 10mm. Divide 360 by 10 and that gives you a magnification power of 36.
You can find eyepieces at many telescope dealers on the internet. Your selection will be far less if you use 0.965" eyepieces. You can purchase 0.965" to 1.25" adapters so that you can use the larger eyepieces with your telescope. However, on some telescopes the adapters will cause the new eyepiece to not come into focus.
You'll also find that eyepiece prices go all over the place. A good general purpose eyepiece is a type called the Plossl. The better eyepieces have more coatings too that allow more light to get through to your eye. You'll find these listed with terms like "fully multi-coated".
Answers & Comments
I am assuming by "lens" you mean eyepieces.
You don't need to get Vivitar brand eyepieces to get additional ones for your telescope. I'm not sure of the specifications for this particular telescope but in general they come in two barrel sizes for the eyepieces. The diameter of your eyepiece is probably 0.965" but could come in the more standard 1.25". You can measure the diameter and determine this quickly.
Once you know the diameter to shop for you can look for the focal length of the eyepiece you wish to purchase. They are rated such as 4mm, 10mm, 25mm, etc. The smaller numbers give you higher magnification. You can calculate the magnification by dividing the telescopes focal length by the eyepiece focal length. For example, let's say your telescope is has a focal length of 360mm and you have an eyepiece rated 10mm. Divide 360 by 10 and that gives you a magnification power of 36.
You can find eyepieces at many telescope dealers on the internet. Your selection will be far less if you use 0.965" eyepieces. You can purchase 0.965" to 1.25" adapters so that you can use the larger eyepieces with your telescope. However, on some telescopes the adapters will cause the new eyepiece to not come into focus.
You'll also find that eyepiece prices go all over the place. A good general purpose eyepiece is a type called the Plossl. The better eyepieces have more coatings too that allow more light to get through to your eye. You'll find these listed with terms like "fully multi-coated".
I hope this helps.
Good luck and clear skies!
-jodair