Equihash 144_5 is a PoW mining algorithm, also known as Zhash. The most popular coin that uses this algorithm is Bitcoin Gold, as well as BitcoinZ. BTG switched to Equihash 144_5 on block 536200 on July 3, 2018. The reason for the switch was pretty common – to protect GPU owners from ASIC invasion. So far there are no ASIC devices on Equihash 144_5. Zhash mining algorithm is available on both the most popular mining power rental services: Nicehash and MiningRigRentals.
Please note that you can not use ASIC-miners for Equihash on Equihash 144_5. It is a different algorithm.