You can get Summer Key ONLY from robux shop right now. In autumn 2024 there was summer key in summer endless and summer battle pass

Units you can get from Summer key:
48.5% - sunscreen

27.7 - chill camera toilet

12% - Beach Speaker Guy

3% - Wave Crusher

2% - Tub Engineer

1.5% - GrillMaster  Chef  Tv ( Morph Token )
1.5% - Beach speaker guy ( Morph Token )

1.5% - Wave crusher camera guy ( Morph Token )

1.5% - Wave ninja camera guy ( Morph Token )

0.5% - Titan SandCastle ( Morph Token )

0.3% - Titan SandCastle

0.01% - Titan Grill Man