は小さいが

is small but

→ は
phrase Rare #29,123
is small but Used to contrast something being small with a positive or contrasting quality. The は marks the topic, 小さい means “small,” and が means “but.”
JA: この部屋は小さいが、居心地がいい。
EN: This room is small, but it is comfortable.

このカメラは小さいが大変優れている

This camera is small but highly capable.

は小さいが強かった

He was small but strong.

私たちの学校の図書館は小さいが新しい

Our school library is small but new.

その家は小さいが私たちには十分だ

That house is small, but it’s big enough for us.