The wearables market continues to gain traction in no small part thanks to the popularity of Apple’s products. The Apple Watch user base is twice as big as that of competitor Fitbit, but surprisingly, it’s one of Apple’s older models that accounts for a bulk of user adoption.

According to Interpret’s New Media Measure®, the Apple Watch Series 3 has the largest installed base among Apple Watch models despite having launched almost three years ago in September 2017. The Series 5 model, which hit the market eight months ago and has new features like an always-on display and a built-in compass, accounts for 18% of the Apple Watch installed base compared with 26% for Series 3, which has maintained steady adoption rates.

Series 3 saw more than 11% of respondents purchase the watch at launch and that figure has held steady at nearly 10% in recent months. Series 5, meanwhile, started out a little better than 6% and has climbed to 7% but has yet to see the levels enjoyed by Series 3.

Apple products often command a premium price, but consumers must weigh feature set, price and overall perceived value when making a purchasing decision. The Series 3 model can now be found on sale for under $200, making it an attractive option when compared to the Series 5 or competing products from Fitbit and others, typically retailing for $150 to $250. It will be interesting to see how Apple alters its design and feature set for the next Apple Watch.