Jim Cramer used CNBC's Mad Money lightning round to favor Avnet while rejecting Archer Aviation and United Microelectronics at current levels, and offering a cautious view on Altimmune. He called Avnet "a really good stock" and highlighted its low P/E (price-to-earnings ratio), although he said investors appear concerned that the stock's advance could soon end. Avnet reported fourth-quarter earnings of $2.28 per share and quarterly sales of $8.295 billion, beating analyst estimates of $1.77 per share and $7.519 billion, respectively. Its shares fell 5.3% to $93.40 on Tuesday. Cramer said United Microelectronics was difficult to assess because the stock is not expensive but has risen 135% this year and lacks a catalyst at current prices. UMC said July net sales increased 18.98% year over year, while sales for the first seven months rose 12.41% to NT$153.61 billion; its shares fell 5.4% to $18.48. Cramer recommended passing on Archer Aviation, saying better speculative trades were available. Archer reported better-than-expected second-quarter sales on Aug. 10 and announced definitive agreements to acquire Boeing's Wisk Aero, SkyGrid and Insitu subsidiaries, while its shares fell 1.1% to $6.32. On Altimmune, Cramer said GLPs are likely to address fatty liver better than other options but would be interested at $2, warning that stocks at that level can still fall to zero.