I'm a huge fan of these they aren't really adequate if you're going to be on your knees all day but way more comfortable than regular knee pads and you always have them with you. Great for those times you have to get down and check something real quick.
Carhartt makes work pants that accept knee pads. The knees have a double front pouch built in. https://dungarees.com/carhartt-b136-double-front-washed-duck-loose-fit-pant
https://www.amazon.com/dp/B00IWZ82AA/ref=cm_sw_r_cp_apa_fabc_HY7SGGX6303DEE905ZNT
Hope this helps.
These are the ones I use.
They usually last 2 or 3 pairs of Carhartts.
https://www.amazon.com/1010-Soft-Knees-Strap-Knee/dp/B00IWZ82AA