Super easy, barely an inconvenience to install.
A while ago I installed an IPS panel, and used one of the pre-cut shells.
I was happy with the results, but it was a pain to keep my rechargable AAs charged, and I had to swap them pretty often.
I got this mod along with the pre-cut battery cover, and it was a breeze to install, looks great, and works great!
Can't stress how neat and modular this battery upgrade is. Definitely recommend this to folks who don't wanna burn through packages on packages of AA batteries (and wallets) while sustainably keeping up with the new V2 IPS screens on the market. The Clean Juice mod elevates old and weary GBAs into long session players.
Easy to install and wonderfully working!
Works like a charm!
CleanJuice Game Boy Advance (V1.1) Li-Ion Rechargeable Battery Module